User:SyG/Archive Budapest

The Budapest Gambit (or Budapest Defence) is a chess opening beginning with the moves 1.d4 Nf6 2.c4 e5. It is rarely played in top-level chess, but is occasionally seen at amateur levels. It has two codes in the Encyclopaedia of Chess Openings, A51 (1.d4 Nf6 2.c4 e5) and A52 (1.d4 Nf6 2.c4 e5 3.dxe5 Ng4).

Black's second move attacks White's centre, sacrificing, at least temporarily, a pawn to do so. White most often will not cling to the extra pawn since that ties his pieces to defence and often gives Black a lead in development. Instead White usually develops his pieces and hopes to gain a lead in development while Black spends time regaining his pawn. After 3.dxe5 (the only serious try for an advantage) Black must move his knight again.

At move 3, Black can try the Fajarowicz variation 3...Ne4!? which concentrates on rapid piece play, but the most common is 3...Ng4, with three main possibilities:
 * The Adler variation 4.Nf3 when after 4...Bc5 5.e3 Nc6 White seeks a spatial advantage in the centre with its pieces.
 * The Rubinstein variation 4.Bf4 when after 4...Nc6 5.Nf3 Bb4+ White has an important choice to make between 6.Nbd2 (giving the pawn back for the bishop pair) and 6.Nc3 (trying to keep the extra pawn).
 * The Alekhine variation 4.e4 when after 4...Nxe5 5.f4 White tries to use the central pawns to seize a big spatial advantage.
 * White also has some other fourth-move possibilities, the most interesting being 4.e3, while the others do not promise much.

Origins
The first known game with the Budapest Gambit is Adler – Maróczy (played in Budapest in 1896). This game already featured some key aspects of the gambit, i.e. active play for the black pieces and White making the typical mistake of moving his queen too soon. As the player of the White pieces was not a strong player, the new opening went unnoticed apart from the local experts who had witnessed the game.

The Hungarians István Abonyi, Zsigmond Barász and Gyula Breyer further developed the opening. Abonyi played it in 1916 against the Dutch surgeon Johannes Esser in a small tournament in Budapest. The Austrian player Josef Emil Krejcik played it against Helmer/Helmar in Vienna in 1917. Carl Schlechter published an analysis of the gambit in the "Deutsche Schachzeitung" (1917, page 242).

The first use of the opening against a world-class player was at Berlin in 1918, when Milan Vidmar played it against Akiba Rubinstein in the first round. Vidmar, having to play Black against such a strong player, was at a loss as to what to play and sought advice from his friend Abonyi, who showed him the Budapest Gambit and the main ideas the Hungarian players had found. Vidmar followed the advice and played one of his most crushing games, beating Rubinstein in just 24 moves.

This victory so heartened Vidmar that he went on to win the tournament, while Rubinstein was so demoralised by this defeat that he lost another game against Jacques Mieses and drew a third one against Schlechter in the same opening.

After this tournament, the gambit finally began to be taken seriously. Top players like Savielly Tartakower and Siegbert Tarrasch started to play it. Schlechter wrote the monograph "The Budapest Defence to the Queen's Gambit", published in 1919 after his death, which can be considered the first book on this opening.

The leading exponents of 1.d4 started to look for reliable antidotes to the gambit. Alexander Alekhine showed how White could get a strong attack with 4.e4 in his games against Ilya Rabinovich (Baden-Baden 1925) and Adolf Seitz (Hastings 1925–26). Rubinstein showed how White could get a small positional advantage with 4.Bf4 Nc6 5.Nf3 Bb4+ 6.Nbd2. Thus, at the end of the 1920s the gambit was considered dubious.

Use by top players
The Budapest Gambit has never been widely used as Black by the top-10 chessplayers:
 * Réti used it three times against lesser opponents, scoring 1½ points.
 * Tartakower used it three times in a unique tournament (Bad Kissingen 1928) but scored only ½ point against very strong opposition (Bogoljubov, Capablanca, Rubinstein).
 * Mieses used it twice, winning against Rubinstein (Berlin 1918) but losing to Euwe (Hastings 1923).
 * Spielmann also used it twice, winning against Euwe (Baden 1922) but losing to Sämisch (Copenhagen 1923).

Some top players experimented with the gambit once against a lesser opponent, with generally good results:
 * Alekhine won against Ibanez (Buenos Aires, 1926).
 * Shirov won against Bacrot (Bosna SuperGM, 2000) when Bacrot was not yet among the world's top players.
 * Flohr won against Staehelin (Bern, 1932).
 * Breyer won against Esser (Budapest, 1916).
 * Maróczy won against Adler (Budapest, 1896).

Some top players used the gambit once against another top player, for the element of surprise and because they reckoned it would not suit their opponent's positional style, generally with good results:
 * Mamedyarov won against Van Wely (Ciudad Real 2004).
 * Short lost against Karpov (Linares, Candidates match, Round 1, 1992).
 * Speelman won against Browne (Taxco, Interzonal, Round 6, 1985).
 * Bronstein won against Tolush (Moscow, USSR Championship, 1944).
 * Schlechter drew against Rubinstein (Berlin 1918).
 * Vidmar won against Rubinstein (Berlin 1918).

Some top players have only used the gambit in their youth, and they have abandoned it when they grew in the chess hierarchy.
 * Svidler used it in 1991–1992 when he was 15 years old.
 * Topalov used it against Dreev in 1989 when he was 14 years old.

Use against top players
Top players have seldom met the gambit:
 * Rubinstein first had catastrophic results in the 1918 Berlin tournament when he made ½/3 against the gambit, but years after he improved by winning against Daniuszewski (Łódź, Poland championship, 1927) and against Tartakower (Bad Kissingen, 1928).
 * Alekhine scored 3/4, with wins over Euwe (Amsterdam, 1921), Rabinovich (Baden Baden, 1925) and Seitz (Hastings, 1926), but a loss against Gilg (Semmering, 1926).

White builds up an imposing pawn centre
In the Alekhine variation White does not try to defend the gambited pawn and concentrates on building an imposing pawn center. This brings him good prospects of a space advantage that is a good basis for a future attack on the kingside. However, Lalic explains that "White must invest valuable tempi in protecting his pawn structure, which allows Black to seize the best squares for his minor pieces with excellent prospects for counterplay against the White center."

Hence in this variation Black lets White build his pawn centre only to undermine it later, according to the teachings of the hypermodern school. The strategic themes are similar to the ones that can be found in other openings like the Four Pawns Attack, the Alekhine Defence or the Grünfeld Defence.

The Budapest rook
The "Budapest rook" is a manoeuvre in the 4.Nf3 variation, when Black has the opportunity to develop its Ra8 aggressively along the sixth rank through the moves a7–a5 and Ra8–a6–h6. For example this can happen after like 1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Nf3 Bc5 5.e3 Nc6 6.Be2 Ngxe5 7.Nxe5 Nxe5 8.a3 a5 9.O-O O-O 10.Nc3 Ra6 11.b3 Rh6.

The rook is then used in a piece attack against White's castled King. Black can easily get several pieces around the white king, notably a rook in h6, a queen in h4 and a knight on g4. The queen arrival on the h4-square is facilitated by the absence of a white knight on the f3-square (that would cover the h4-square) and of a black knight on the f6-square (that would block the way for the black queen). If White tries to defend with h2–h3 then the Bc8 can be sacrificed in h3 in order to open the h-file.

The Bc5 does not seem particularly useful in this attack, but by eyeing e3 it makes it difficult for White to play f4 to remove the black knight, and the attack on e3 is sometimes reinforced with heavy-piece doubling on the e-file. Moreover there are several motives of sacrifice on e3. Besides, the Bc5 can sometimes be recycled on the b8–h2 diagonal via Bc5–a7–b8, to put even more pressure on h2. It can also stay on the a7–g1 diagonal to put pressure on f2, if White pushes e3–e4 at some stage.

The "Budapest rook" was an invigorating innovation of the 1980s, and gave the gambit new life. However, inconveniences do arise from delaying d7–d6 in order to allow the lift: the light-square bishop has to wait a long time for development, and any attack on the Bc5 is potentially annoying for Black (since it means either closing the sixth rank with ...d6/...b6, abandoning the active a7–g1 diagonal, or getting in the way of its rook on a7). This, in addition to the risk of awkwardness in the king side (a knight on f5 will fork the Rh6 and the Qh4) and the single-mindedness of Black's plan (with nothing to fall back on if the direct attack is repelled), has made some miss the old lines, where it is the king's rook that goes to h6. The queen's rook can then be used on queenside operations (after, for example, the retaking the Bc5 with the b-pawn).

The advantages of ...Bb4+
In most variations Black has the opportunity to play Bb4+. The advisability of this check depends on White's possible answers:
 * If White has to play Nb1–c3 then Black should capture the Nc3 only if White is forced to take back with the b2-pawn. Then the isolated, doubled pawns on c3 and c4 are a positional advantage for Black that fully compensates the loss of the bishop pair, and even the gambitted pawn. Black will also use the c5-square as a stronghold for his pieces that White cannot contest with pawn attacks. Exchanges of pieces can be good for Black even if he is a pawn down, as he can hope to exploit the crippled pawn structure in the ending. On the other hand, if White can take back with another piece (e.g. a Rook in c1, or a Bishop in d2), the capture of the Nc3 by Black would be bad as it would just lose the bishop pair.
 * If White has to play Nb1–d2 then it is sometimes a minuscule positional concession, as it makes it harder for this knight to reach its ideal square d5. However, if Black is later compelled to exchange Bxd2, that is advantageous to White who thereby wins the bishop pair. Besides, in some situations the Bb4 could be as misplaced as the Nd2.
 * If White has to play Bd2 then Black should exchange the bishops only if White is forced to recapture with the Nb1, because then this knight is slightly misplaced to reach its best square d5.

First example : in the Alekhine variation, after 1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.e4 Nxe5 5.f4 Ng6 6.Nf3, the move 6...Bb4+ (see diagram on right) is good because White has no good reply apart from 7.Nc3: After 7.Nc3 Black can either answer with 7...Bxc3+ 8.bxc3 or with 7...Qf6, attacking both c3 and f4.
 * 7.Nbd2? just loses a pawn after 7...Nxf4;
 * 7.Bd2?! Qe7! causes White great problems: both the pawns in f4 and e4 are attacked, and 8.Bxb4 Qxb4+ results in a double attack against b2 and f4.

Second example : the game Döry – Tartakower (Vienna 1928) saw the first moves 1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.e3 Nxe5 5.Nf3 when the players continued with 5...Bb4+ 6.Bd2 Bxd2+ 7.Nbxd2 Nbc6 with equality. This sequence is fraught with errors:
 * 5...Bb4+?! is bad because White is not forced to play 6.Bd2, and can instead play 6.Nbd2 to avoid the exchange of bishops and gain a tempo later with a2–a3, with a small plus.
 * 6.Bd2?! allows 6...Bxd2+!, giving Black the opportunity to exchange the bishops while placing the Nb1 on a second-best square. White cannot take back with his queen, as 7.Qxd2?! Nxf3+ 8.gxf3 would ruin White's kingside pawn structure.

Third example : in the Adler variation after 1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Nf3 Black should not play 4...Bb4+ because White can answer 5.Nbd2! Nc6 6.e3 Ngxe5 7.Nxe5 Nxe5 8.a3! Bxd2+ 9.Qxd2 and White has the better prospects. He has the bishop pair and he can develop his Bc1 on the powerful a1–h8 diagonal.

The pressure against the e4-square and the e3-pawn
In the 4.Nf3 variation, when White has moved f2–f4, the e3-pawn becomes a backward pawn on an open file. Black can then apply pressure on the e-file in general, against the e3-pawn and the e4-square in particular.

Typical moves in this plan would include the manoeuvre Ne5–d7–f6, and putting the heavy pieces on the e-file with Rf8–e8 and Qd8–e7. The Bc5 is already well placed to pressure the e3-pawn. Depending on circumstances, the Bc8 may be involved either in b7 either in f5, in both cases to control the e4-square.

This plan can be investigated only if some conditions are met:
 * the d7-square is available for the Ne5, so that it can go in f6 latter.
 * White cannot easily advance its e3-pawn in e4, where it would be adequately be defended by the Nc3 and a possible Bf3.
 * White does not have the time to launch a quick attack on Black's castle with f4–f5–f6.

The c4–c5 push
In the main lines the pawn push c4–c5 often brings positional gains to White.

In the Rubinstein variation with 6.Nbd2, after 7.a3 Ngxe5 8.Nxe5 Nxe5 9.e3 Bxd2+ 10.Qxd2 (see diagram at right) White gets the bishop pair and a space advantage. In order to build up on these characteristics the most used plan is to perform a minority attack on the queenside, with the goal of performing the push c4–c5 in good conditions.This push can give several advantages to White: For example after the natural but mistaken 10...O-O?! (diagram on right) White can immediately realise his strategic goal with 11.c5! Therefore Black generally tries to hinder the c4–c5 push with moves like d7–d6, b7–b6 or Rf8–d8 (if this creates a hidden vis-à-vis between the Rd8 and the Qd2)
 * enhance the prospects of his light-square bishop,
 * create a half-open file to attack with the rooks,
 * create an isolated, backward pawn in d6 after the exchange c5xd6.
 * If Black accepts the temporary sacrifice, after 11...Qxc5 12.Rc1 Qd6 13.Qxd6 cxd6 14.Rd1 White gets his pawn back and has created a weak pawn in d7.
 * If Black refuses the pawn he has difficulties to develop his queenside, for example 11...d6 would be followed by 12.cxd6 Qxd6 13.Qxd6 cxd6 and the pawn on d6 is weak.

Similarly, in the Adler variation, after 4...Bc5 5.e3 Nc6 6.Be2 O-O 7.O-O Re8 8.Nc3 Ngxe5 9.b3 a5 10.Bb2 Nxf3+ Bxf3 Ne5 12.Be2 Ra6 13.Qd5 Qe7 14.Ne4 Ba7 (see diagram on right) White has a good opportunity to push 15.c5, because this move:
 * closes the diagonal of the Ba7 for now,
 * makes it harder for Black to develop the Bc8, as a push b7–b6 (respectively d7–d6) may be answered by cxb6 (respectively cxd6), creating a weak pawn for Black,
 * and enhances the prospects of the Be2.

In the Rubinstein variation with 6.Nc3, White is saddled with doubled pawns in c3 and c4 that limit the scope of his bishop pair. Hence the push c4–c5 can be used to free the light-squared bishop and disrupt Black's position.

The Kieninger Trap
The Kieninger Trap is a chess trap named after Georg Kieninger who used it in an offhand game against Godai at Vienna in 1925.

In the Bernstein line, after 6...Qe7 7.a3 the Bb4 is attacked but Black does not have to move it for the moment, and instead both regains the gambit pawn, and sets a trap, with 7...Ngxe5. White seems to win a piece with 8.axb4?? but that in fact runs into the Kieninger trap 8...Nd3 checkmate.

After 8.Nxe5 Nxe5 White still cannot take the Bb4 because there is still the threat of 9...Nd3 checkmate. So this trap (and passive sacrifice) is in force during two moves.

A rare variant has also occurred in a miniature in the Fajarowicz variation, after the moves 1.d4 Nf6 2.c4 e5 3.dxe5 Ne4 4.Qc2 Bb4+ 5.Nd2 d5 6.exd6 Bf5 7.Qa4+ Nc6 8.a3 Nc5 9.dxc7 Qe7! when White, trying to save his queen, fell into 10.Qd1 Nd3 checkmate.

Adler variation 3...Ng4 4.Nf3
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Nf3

The Adler variation is named after the game Adler – Maróczy which was played at the 1896 Budapest tournament. White is ready to give up the e5-pawn in order to develop all his pieces on their best squares, i.e. the d5-square for the Nb1, the f3-square for the Ng1 and the a1–h8 diagonal for the Bc1.

In the main line 4...Bc5 the f2-pawn is attacked, forcing 5.e3 that blocks the way for the Bc1. Then after 5...Nc6 White has not enough pieces to protect his e5-pawn on the long run, e.g.:
 * 6.Qd5?! is a doomed attempt, exposing the queen and occupying the d5-square that should belong to the Nb1. This move has a historical interest as this was the line played in the first game where the Budapest Gambit occurred. Black continues calmly with Qe7/Ngxe5/d6/Be6.
 * 6.Bd2 O-O 7.Nc3 Qe7 does not prevent Black to regain his pawn either, and it obstructs the way to the d5-square for the Nb1. Once he has the pawn back Black has equality.
 * 6.b3 immediately allows Black to play 6...d6! when White cannot capture in d6 because of Qd8–f6 winning the Ra1. Play will likely transpose into the 6.Be2 variation.

An important theoretical decision for White is to choose whether he wants to make a2–a3 part of his plan or not. While this move avoids any possible Nc6–b4 and creates the possibility b2–b4, it may also be seen as a possible waste of time in some lines. As Lalic puts it:"It was not so long ago that 8.a3, with the obvious intention of expanding with b2–b4, was the standard move. However, after Black responds with the logical a7–a5, it became apparent in tournament practice that the inclusion of these moves is in fact in Black's favour, as it gives his queen's rook access into play via the a6-square."

Black can also try the minor line 4...Nc6 that allows Black to delay the development of the f8-diagonal depending on the circumstances, and allows White to transpose into the 4.Bf4 variation if he wishes to do so.

The 4...Bc5 line with a2–a3
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Nf3 Bc5 5.e3 Nc6 6.a3

After the standard moves 6...a5 7.b3 O-O 8.Bb2 Re8 9.Nc3 Ngxe5 10.Nxe5 Nxe5 11.Be2 d6 12.O-O both kings are in safety and Black has regained the invested pawn in the process. Both players can deviate at various points but the positions reached are similar, e.g. in one game White played an early Ra1–b1 in order to push b2–b4 in one move, but Black continued with the same plan as explained hereunder. In another game White developed his Bf1 in d3 instead of e2, but this gave the opportunity for Black to sacrifice the Ng4 on the f2-pawn before the white castle.

White has a space advantage in the center and can initiate pressure here or on the queenside by some pawn pushes like b3–b4 and c4–c5 (possibly supported by a knight on the d5-square). Meanwhile, the White king lacks some defenders so Black can start a pieces-driven attack with the standard "rook lift" (see the chapter on "Strategic and tactical themes"). As Tseitlin puts it, "the point is that 6...a5 fits into the plan of attacking White's kingside (!), whereas 6.a3 does little in the way of defending it". Thus if White does not find a clear way to make good use of his move a2–a3, it may turn out to be a waste of tempo.

After 12...Re6 White has to chose a way to react to the oncoming assault:
 * 13.Nd5 Rh6 14.g3 (to avoid the crushing 14...Qh4) 14...Bh3 15.Re1 when the Nd5 seems excellently placed, supporting the b3–b4 push on the queenside and one jump away from the f4-square where it can cover the weak light squares h3 and g2 if needed. Nevertheless, after 15...c6!? 16.Nf4 Bf5 it may be difficult for White to realise the b3–b4 push and the weakness of the d6-pawn is not of great significance as long as White cannot attack it with his minor pieces, so chances are level. Thus placing the Nc3 in d5 may be premature.
 * 13.g3 Rh6 14.Ne4 seems crushing as White threatens to win both the Bc5 and the Ne5 (the d6-pawn is pinned). Moreover the Ne4 is well placed to support a later c4–c5 push. Black must react with 14...Qd7 in order to get out of the pin and continue the initiative. Now White has to lose a tempo and weaken his kingside further with 15.h4 in order to avoid the terrific threat Qh3–Qxh2#. After 15...Ba7 Black has dynamic equality.
 * 13.Na4 is another try for White, hindering Re6–h6 because of Bxe5. Black must switch to defence on the queenside with 13...b6!? 14.Nxc5 bxc5 15.f4 (necessary to improve the prospects of the Be2) Nd7 16.Bf3 Rb8 17.Qd3 a4! when Black is even better. In this plan it is important that Black does not fear to move his imprisoned Bc5, e.g. 14.Bc3 (threatening 15.b4) 14...Bd7 15.b4? Bxa4 16.Qxa4 axb4.

The 4...Bc5 line without a2–a3
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Nf3 Bc5 5.e3 Nc6

In this variation White reasons that the advance a2–a3 is only a loss of time, because Black will play a7–a5 anyway. By refraining from the advance a2-a3 White tries to gain a tempo on the lines of the previous section, to make it more difficult for Black to initiate the Re8–e6–h6 lift. For example after the typical 6.Be2 O-O 7.O-O Re8 8.Nc3 Ngxe5 9.Nxe5 Nxe5 10.b3 d6 11.Bb2 Re6 12.g3 Rh6?! 13.Ne4 Qd7 14.h4 Black does not have the a7-square for his Bc5 because he had no time to play a7–a5. As we shall see, however, a rook lift is still one of the best options for Black.

White generally continues with 6.Be2, but can instead try the tricky 6.Nc3. The immediate recapture 6...Ngxe5?! 7.Nxe5 Nxe5 allows 8.f4! Nc6 9.Bd3 when the white bishop is much more actively placed than on e2. However, simply 6...O-O! 7.Be2 Ngxe5 transposes to the 6.Be2 move-order.

Note that Black should recapture the e5-pawn first with the Ng4, not the Nc6. Lalic analyzes 6.Be2 O-O 7.O-O Ncxe5?! 8.Nd4! (attacking the Ng4), when 8...Nf6 leaves Black without a clear plan and "White can expect an opening advantage". Alternatively, 8...Qh4 gives White a positional advantage with 9.h3 Nh6 10.Nc3 d6 11.Nd5 ("!" Lalic) to bring the knight back to f4 in case of a Black sacrifice in h3.

After the standard moves 6.Be2 O-O 7.O-O Re8 8.Nc3 Ngxe5 9.Nxe5 Nxe5 White has tried two different plans:
 * The older fianchettoes the Bc1 and then plays in the centre with moves like Qd1–d5, Nc3–e4 and c4–c5. White attains a huge central space advantage, but Black can attack the kingside with the usual Ra8–a6–h6 rook-lift.
 * More recently, White has tried leaving the bishop on c1 for a time, and starting a kingside blitzkrieg with moves like f2–f4, Be2–d3 and Qd1–h5. In this line, Black tries to exploit White's weak pawn on e3.

Instead of the usual 6.Be2 White has also tried developing the queenside first, but it is dangerous to leave White's king in the centre too long. After 6.b3 O-O 7.Bb2 Re8 8.Bd3 ("?!" Lalic) d6 ("!" Lalic) 9.exd6? Nxf2! 10.Kxf2 Rxe3 11.Kf1 Bg4 Black had a crushing attack.

White attacks in the centre
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Nf3 Bc5 5.e3 Nc6 6.Be2 O-O 7.O-O Re8 8.Nc3 Ngxe5 9.Nxe5 Nxe5 10.b3

After 10.b3 a5 White can try to capture the Bc5 with 11.Na4 or 11.Ne4, one point being that the retreat 11...Ba7 would lock the Ra8 because Black has not played Ra8–a6 already. Nevertheless, Lalic still thinks 11...Ba7 is the right move after 11.Ne4 due to the importance of the a7–g1 diagonal. However, Black can also reroute the bishop with 11...Bf8 and "White has no obvious path to even a minute advantage". After 11.Na4 Black can also simply react by 11...b6 when the loss of the bishop pair is compensated by the semi-open B-file and the improved control on the central squares. Tseitlin considers that after the exchange in c5 Black has the better position. That is why the most common White move is 11.Bb2, keeping the knight jumps for later.

Then the most common plan for Black is a rook lift: the plan Ra8–a6–h6 was tried in the much-commented game Åkesson – Tagnon (Berlin Open 1984). Black duly won, but after the game continuation 11...Ra6 12.Qd5! Qe7 13.Ne4 Ba7 14.c5 Rg6 15.Rac1 Bb8 16.f4 authors do not agree on which side had the advantage. Borik considers that White had a positional advantage, Tseitlin agrees and recommends 15...Nc6! instead of 15...Bb8, with dangerous threats. However about 15...Bb8 Lalic says "it is true that the bishop pair look a bit pathetic lined up on the back rank just now, but there is no way to stop them breaking out later".

In fact, after 11...Ra6 much depends if White goes for the moves Qd1–d5 and Nc3–e4, or deviates with Nc3–a4:
 * After 12.Qd5 several games saw 12...Ba7. A game from Kramnik (playing as Black) saw 13.Ne4 Rae6 14.Ng3 d6 15.Qxa5 Bb6 16.Qc3 Rh6 and "Black has obtained a powerful attacking position in terurn for the pawn sacricice" according to Tseitlin. In another game, White varied with 13.Ne4 Rae6 14.c5!?, when Tseitlin recommends the tactical 14...d6 15.cxd6 c6 16.Qd1 f5 17.Bxe5 Rxe5 "with good prospects for Black". Another attempt for White is 13.Ne4 Rae6 14.Qxa5 Bb6 15.Qc3 Qh4, when Tseitlin writes that 16.f4 is "the only move that enables White to organise resistance", while Lalic considers the move dubious, saying "16.Ng3 offers more resistance". Kasparov presented the line 13.c5 Rh6 14.f4 Qh4 15.h3 as being worth consideration. Black had had trouble finding a good square for his attacked knight in a 1988 Yugoslav game, where 14...Nc6 lost quite quickly; hence the try 14...Qh4!?, attacking h2. Also unclear is acceptance of the piece sacrifice with 15.fxe5 Qxh2+ 16.Kf2, when Black obtains definite compensation in a very sharp position.


 * Even if 12.Qd5 Ba7 is fully satisfactory for Black, Lalic still considers 12...Qe7 best, and on 15...Bb8 he says "it is true that the bishop pair look a bit pathetic lined up on the back rank just now, but there is no way to stop them breaking out later". When White tries a different move-order with 12.Ne4 Ba7 13.Qd5, Black usually opts for 13...Rae6, a promising pawn sacrifice. After the possible 14.Qxa5 Bb6 15.Qc3 Qh4 only 16.f4 enables White to organise resistance.

White attacks on the kingside
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Nf3 Bc5 5.e3 Nc6 6.Be2 O-O 7.O-O Re8 8.Nc3 Ngxe5 9.Nxe5 Nxe5 10.Kh1

The plan of attacking on the kingside was unveiled by Spassky in a game against Illescas (Linares 1990). Black did not understand immediately White's idea, so that after 10...a5?! 11.f4 Nc6 12.Bd3 d6 13.Qh5 (awarded a "!" by Lalic) 13...h6 14.Rf3 Black's pieces were ill-placed to counter White's attack.

A more principled plan for Black is to react by an action on the centre, specifically against the backward e3-pawn. After 10...d6 11.f4 Nd7 ("!" Lalic) 12.Bd3 Nf6 13.Qf3 Ng4 14.Nd1 f5 ("!" Lalic) and Black has succeeded in avoiding White's expansion e3–e4.

The 4...Nc6 line
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Nf3 Nc6

Black plays this when he wants to postpone the placement of its dark-squared bishop. Now White has a wide choice:
 * 5.Bf4 transposes in the 4.Bf4 variation explained hereafter.
 * 5.Qd5 transposes in the minor line 4.Qd5 explained hereafter.
 * 5.e3 and now 5...Bb4+ is not that good because White can react with the simple 5.Bd2. Better for Black is 5...Ngxe5 when Black can go into a kind of King's Indian Defence setup with g7–g6 and Bf8–g7. Then the pressure along the a1–h8 diagonal can be enhanced via the quick advance a7–a5–a4–a3. For example after 5.e3 Ngxe5 6.Be2 g6 ("!?" Lalic) 7.O-O Bg7 8.Nc3 O-O 9.Qd2 d6 10.h3 ("?" Lalic) 10...a5 ("!" Lalic) 11.b3 a4 and now 12.Bb2 would have been followed by 12.a3! 13.Bc1 Nxf3+ 14.Bxf3 Qf6 winning the Nc3.
 * 5.Nc3 will transpose into the 4...Bc5 line if Black plays 5...Bc5, but Black can also wait a bit to see what White is up to, e.g. 5...Ngxe5 6.Nxe5 Nxe5 7.Qc2 Bb4 when both players are still hesitating to castle long or short.
 * 5.Bg5 Be7 6.Bxe7 (6.Bf4 Bb4+ transposes in the 4.Bf4 variation) 6...Qxe7 7.Nc3 with the dangerous positional threat Nc3–d5. Here Borik advocates 7...Qc5 8.e3 Ngxe5, when he can react to Qd1–d5 with Qc5–e7 (and the d5-square is no more available to the Nc3), and to Nc3–d5 with Nc6–e7 (to exchange the annoying knight). Black can also delay the recapture of the e5-pawn with 7...O-O 8.Nd5 Qd8 9.e3 Ngxe5 10.Nxe5 Nxe5. Meanwhile, the natural 7...Ngxe5 falls into White's positional trap and after 8.Nd5 ("!?" Lalic) 8...Qd8 9.Nxe5 Nxe5 10.Qd4 f6 11.f4 Ng6 12.Qe4+ Kf7 White got an edge.

Rubinstein variation 3...Ng4 4.Bf4
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4

This is called the "Rubinstein variation" in reference to the famous game Rubinstein – Vidmar (Berlin 1918), where the move 4.Bf4 was first employed. The move 4.Bf4 first aims to be able to answer 4...Bc5 with 5.e3 without blocking the Bc1, contrary to what happens in the Adler line 4.Nf3. On the other hand, the early development of the bishop means that White is slightly exposed to a Bb4+.

Also, in the Adler line White faces the risk of a strong attack against his kingside (see section "The rook lift" in the strategic themes), while in the 4.Bf4 variation this is seldom the case because White's Bf4 is well placed to protect White's kingside if needed. However in some cases the Bf4 can become slightly exposed (e.g. some variations of the Rubinstein line when Black plays g7–g5 and h7–h5).

Apart from the sideline 4...g5, the main line continues with both camps developing their pieces around the e5-pawn with 4...Nc6 5.Nf3 Bb4+ (preparing 6...Qe7) when White has an important choice to make between the two moves 6.Nc3 and 6.Nbd2, each leading to extremely different play. With 6.Nc3 White accepts to have his pawn structure on the queenside ruined, in return for a material advantage of one pawn, the bishop pair and active play in the center.

On the other hand, with 6.Nbd2 White gives back the gambited pawn in order to keep a healthy pawn structure and to get the bishop pair. After 6...Qe7 White generally plays 7.a3 in order to force the immediate exchange of the Bb4 for the Nd2 and get the bishop pair, a space advantage and a minority attack on the queenside. White can also try 7.e3 which tries to win a tempo over the 7.a3 variation but may end up with the Bb4/Nd2 exchange made in less favourable circumstances, or not made at all. The maverick gambit 6...f6 also exists.

The sideline 4...g5
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 g5

The sideline 4...g5!? was not well regarded at the end of the 20th century. Borik wrote that "the move 4...g5 creates irreparable weaknesses in Black's camp", while Tseitlin decided "this extravagant tactical stroke weakens the kingside and, on general ground alone, cannot be good". Lalic warned that "Black should be aware of the risks he is taking by playing such a line". Nonetheless, the 4...g5 line has found new supporters in recent years, thanks to Black's wins in Van Wely – Mamedyarov, Ciudad Real 2004 (where White played 5.Bg3), and Graf – Asik, Kavala 2007 (where White played 5.Bd2).

The main reason why 4...g5 was not well considered is that this move weakens a lot of squares, mostly f5 and h5 (as they cannot be covered by the g-pawn anymore). White can try to exploit these weaknesses with the manoeuvres Bf4–d2–c3 (pressure along the diagonal a1–h8), Ng1–e2–g3–h5 (pressure against the squares f6 and g7) and h2–h4 (to open the h-file).

The retreat 5.Bg3
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 g5 5.Bg3

For years, the reaction 5.Bg3 was not well considered because it does not make the most out of Black's provocative fourth move. Tseitlin considered that "the bishop is in danger of staying out of play for a long time". But later Lalic found that 5.Bg3 was "just as effective" as 5.Bd2. Black concentrates on getting his pawn back, while White tries to get an advantage from the weakening of the black kingside. After the possible 5...Bg7 6.Nf3 Nc6 7.Nc3 Ngxe5 8.Nxe5 Nxe5 9.e3 d6 White has tried several ideas: White has also tried to quickly open the h-file with 7.h4 Ngxe5 8.Nxe5 Nxe5 9.e3 but after 9...g4! Black succeeded in keeping the file closed.
 * After 10.h4 h6 Tseitlin considers that Black has a satisfactory game.
 * After the natural but inoffensive 10.Be2?! Be6 Tseitlin thinks Black already has equality.
 * White also tried 10.Rc1, to remove the latent positional threat Bxc3 (that would double White's queenside pawns), indirectly cover the c4-pawn, ease the c4–c5 push in a distant future notably if Black castles on the queenside). After 10...Be6 11.b3 h5!? 12.h4 Ng6 13.hxg5 Qxg5 Lalic assesses that "White must be fractionally better due to the potential weakness of Black's h-pawn".
 * Lalic considers the best try to be 10.c5!, sacrificing a pawn to weaken Black's control on the e5-square and expose the black king further. The game Fraschini – Fuentes (Cuba 1995) continued with 10...O-O 11.cxd6 cxd6 12.Be2 Qb6 13.Qd2 Be6 14.O-O and Black felt compelled to complicate things with 14...d5!? to avoid being slowly constricted on the d-file.

The retreat 5.Bd2
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 g5 5.Bd2

The retreat 5.Bg3 is less considered than 5.Bd2 (in order to place the bishop on the wide-open diagonal a1–h8), after which "White can expect a safe advantage". Then according to Lalic delaying the recapture with 5...Bg7 6.Bc3 Nc6 7.e3 Ngxe5 is not correct as White can gain an advantage by 8.h4 or 8.Qh5, so the immediate 5...Nxe5 is better. For some time 6.Bc3 was well considered because Black had problems to deal with the various positional threats: However the correct way for Black was found in 5...Nxe5 6.Bc3 Qe7 7.e3 Rg8! 8.Nf3 Nbc6 9.Be2 d6 10.Nd4 Bd7 11.b4 g4 with good counterplay for black on the kingside.
 * After 6...Bg7 7.e3 White already threatens to win a piece with the advance f2–f4. After 7...g4 8.Ne2 d6 9.Nf4 h5 10.Qc2 Joseph Staker suggests 10...Qg5 but play can continue by 11.Nd2 Bf5 12.Qb3 b6 13.c5! O-O 14.cxd6 cxd6 15.h4 Qh6 16.g3 Nbc6 17.Bg2 Rac8 18.O-O and White stands better thanks to the weaknesses in h5 and d6. Black has also tried 10...Na6 but it did not solve his problems.
 * After 6...Qe7 7.e3 Bg7?! White unleashes 8.h4! and Black has a creepy choice between 8...g4 (that would give the excellent f4-square for a white knight) and 8...h6 9.hxg5 hxg5 10.Rxh8+ Bxh8 11.Qh5 with advantage for White.

White's efforts then switched to 6.Nf3 to open the e-file, something that Black cannot really avoid as 6...Bg7 7.Nxe5 Bxe5 8.Bc3 would leave an advantage to White. For example 8...Qe7 9.Bxe5 10.Qxe5 10.Nc3 d6 11.e3 and Black is at a loss for an equalising line, White's advantage consisting in his ability to install his knight on the strong d5-square and to attack the weakened Black's kingside with the advance h2–h4. It is better for Black to continue with 6...Nxf3+ 7.exf3 when both 7...h5? and 7...Bg7 would fail to 8.Qe2+, so Black must try 7...d6 8.Qe2+ Be6 instead.

The line 6.Nc3
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 Nc6 5.Nf3 Bb4+ 6.Nc3

This line is called the "Kornl Richter gambit" by the chess historian Bill Wall. ; this is the only line of the Budapest gambit in which Black cannot regain his pawn for sure. Black does best to immediately exchange the Nc3 with 6...Bxc3+ 7.bxc3 as otherwise White gets a small positional advantage simply by avoiding the doubled pawns (see "The advantages of ...Bb4+" in the chapter "Strategic and tactical themes"). Then Black can put pressure on the e5-pawn with 7...Qe7 when White's only possibility to keep the pawn is 8.Qd5. White threatens to ease the pressure with the move h2–h3 that would put the Ng4 on the unfavourable square h6, so Black's only possibilities to sustain the initiative are 8...Qa3 and 8...f6.

The line 8...Qa3 puts pressure on the white queenside pawns, this pressure can latter be reinforced with Nf6–e4. The black queen can also access to the a5-square at some point, where it puts pressure on the e1–a5 diagonal towards the white king. After 9.Rc1 f6 10.exf6 Nxf6 11.Qd2 d6 12.Nd4 O-O we reach the position of the famous game between Rubinstein and Vidmar, when Rubinstein erred with 13.e3? and lost. After the better 13.f3 the correct method for Black is to target the c4-pawn with the regrouping Ne5/Qc5. Hence Lalic thinks 11.Qd2 is inappropriate and gives Black excellent counterplay, and prefers 11.Qd3 or even 11.Qd1!? instead. After 11.Qd3 O-O 12.g3 d6 13.Bg2 Black should switch to a materialistic mode with 13...Qxa2.

In the other line 8...f6 Black does not want to decentralise his queen and prefers to concentrate on an active piece play in the centre. After 9.exf6 Nxf6 all three queen retreats 10.Qd1, 10.Qd2 and 10.Qd3 are possible but each of them has its own drawbacks: on d1 the queen is not developed, on d3 it is exposed to Bc8–f5 and on d2 it is exposed to Nf6–e4. Lalic considers 10.Qd3 to be the main move, qualifies 10.Qd1 as a "respectable option", but considers 10.Qd2 as "inaccurate", giving the line 10...d6 11.e3 Ne4 12.Qc2 g5 13.Bg3 Bf5 14.Bd3 h5 with the initiative for Black.

Meanwhile Black will try to create counterplay by attacking either the weak c4-pawn, or the kingside with g7–g5 and h7–h5. In both cases a key possibility is the move Nf6–e4 that centralises the knight, attacks the weak c3-pawn, controls the c5-square and supports the g7–g5 thrust.
 * In the case of 10.Qd1, the game may continue with 10...d6 11.e3 O-O 12.Be2 Ne4 13.Rc1 Kh8 and White does better to avoid 14.O-O?!, when 14...g5 launches a powerful attack.
 * After 10.Qd3 d6 11.e3 Ne4 12.Be2 O-O 13.Qc2 Nc5 14.Nd4 Ne5 15.O-O Black can start to press the c4-pawn with Qe7–f7. Another idea for Black after 10...d6 11.e3 O-O 12.Be2 is the push 12...b6, developping the light-squared bishop on the a8–h1 diagonal instead of the more usual developments on d7, f5 or g4. The game continued 13.O-O Kh8 14.Qc2 Bb7 15.Nd4 Ne5 16.Rae1 Rae8 17.Bg5 Qf7 18.Bxf6 gxf6! and Black used the g-file and his Bb7 to attack White's king. As the development 11.e3 12.Be2 leaves his light-squared bishop a bit passive, White can improve its prospects with 11.g3 O-O 12.Bg2 and a possible attack along the a8–h1 diagonal. For example after 12...Ne4 13.O-O Nc5 14.Qe3 Be6 the freeing move 15.Nd4! allows White to seize the initiative. That is why Black should avoid the natural manoeuvre Nf6–e4–c5 and prefer 12...Bg4! instead, to immediately puts pressure on the e2-pawn. After 13.O-O Rae8 14.Rfe1 Kh8! the struggle continues. White has also tried 10.Qd3 d6 11.Bg5 to give up the bishop pair in return for better control on the centre and the e4-square, and after 11...O-O 12.e3 Lalic recommends 12...b6 to occupy the a8–h1 diagonal.

On the way till 10...d6
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 Nc6 5.Nf3 Bb4+ 6.Nbd2 Qe7 7.a3

The Bb4 is attacked but Black does not have to move it for the moment, and instead plays 7...Ngxe5 to get the gambitted pawn back. Now Black threatens both to take the c4 pawn and to take the Nf3, when White will either have to accept doubled pawns or move his king. For example this is seen after 8.e3?! when 8...Nxf3+ forces either 9.gxf3 or 9.Qxf3 Bxd2+ 10.Kxd2, when White cannot castle anymore.

White cannot play 8.axb4?? because of the Kieninger trap 8...Nd3 mate (see the section on "Strategic and tactical themes"). White does not want to play 8.Bxe5?! either because it would lose the bishop pair, which is the main source of White's hopes for an advantage in the Bernstein line. So White is more or less forced to exchange a pair of knights with 8.Nxe5 Nxe5.

White still cannot win a piece with 9.axb4?? because the mate threat by Nd3# is still in force. White also cannot win a piece by 9.Bxe5?! because Black would play the zwischenzug 9...Bxd2+ 10.Qxd2 Qxe5 with an equal game. White accordingly plays 9.e3 in order to protect the c4-pawn that was attacked by the Ne5.

Now there is no more mating threat on d3 so the Bb4 is really attacked and Black has to move it. 9...Bd6 (or 9...Bc5 10.b4 Bd6, intending to meet 11.c5?! with 11...Nd3+ 12.Bxd3 Bxf4) would misplace the bishop, and 9...Ba5?? would lose the bishop to 10.b4 Bb6 11.c5. That leaves 9...Bxd2+, when after 10.Qxd2 we get the real starting position of this variation.

It is important to note that for Black, the sequence 7...Ngxe5 8...Nxe5 9...Bxd2+ is not only cunning, but also the best move-order as another sequence would give White an early opportunity to realise the advantageous c4–c5 push (whose advantages are explained in the section "Strategic and tactical themes"). For example after 7...Bxd2+?! 8.Qxd2 Ngxe5 9.Nxe5 Nxe5 White should not play the usual 10.e3?! but should strive for more with the immediate 10.c5! as Black cannot take in c5 without losing the c7-pawn (because of the possibilities Ra1–c1 and Qd2–c3).

After 10.Qxd2, Tseitlin explains that "opening manuals assess this position as favourable to White on the basis of the bishop pair. However, considering the closed nature of the position, White faces substantial difficulties in the realisation of this nominal advantage." Black has not a lot of things to be proud of as there are no targets in White's camp, but can put up a lot of resistance thanks to some small assets:
 * Black's Ne5 is strongly centralized, attacks the c4-pawn, and restricts the Bf1 from moving to the natural squares d3 and f3. Moreover, exchanging the knight with Bxe5 is not appealing for White, since that would mean losing the advantage of the bishop pair.
 * the Bc8 can sometimes become better than its counterpart the Bf1, if it makes it to the good squares b7 or c6 while the Bf1 remains restricted by the Ne5.

This explains the most natural plans for both sides. White will try a minority attack on the queenside, in order to increase its space advantage and to create some weaknesses in the black pawns (e.g. an isolated pawn or a backward pawn). So White will try to use the advances b2–b4 or c4–c5 in good conditions, supported by the queen and the rooks on the c-file and the d-file. On the other hand, Black will try to keep the position closed, most importantly keep the c4-pawn where it is in order to keep the Bf1 at bay. This can be achieved by moves like b7–b6 and d7–d6, and sometimes the manoeuvre Ne5–d7–f8–e6.

The first move by Black has to be 10...d6! because otherwise White plays 11.c5! and gets a clear advantage immediately. For example 10...b6? loses a pawn to 11.Qd5 Nc6 (forced) 12.Bxc7, and 10...O-O?! is bad because of 11.c5! when Black should not take with 11...Qxc5? because of 12.Rc1 Qe7 13.Rxc7 and White is winning already.

The battle for the c4–c5 push
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 Nc6 5.Nf3 Bb4+ 6.Nbd2 Qe7 7.a3 Ngxe5 8.Nxe5 Nxe5 9.e3 Bxd2+ 10.Qxd2 d6

After 10...d6! White can try (and has tried) about any move that goes into the direction of the aforementioned plan. In particular White has to chose if he wants to start active operations on the queenside immediately (e.g. Rc1, Qc3, c5), or if he wants to finish his development first (with Be2 and O-O).

The immediate 11.c5!? is a possible pawn sacrifice in order to open some diagonals for the bishops. As Lalic points out, "after 11...dxc5 Black's knight on e5 has lost its support and therefore all tactical motifs based on Qd5 and Bb5+ must be carefully checked". White gets a powerful attack for his pawn but nothing decisive, for example 11...dxc5 12.Qd5 Nc6! 13.Bb5 O-O 14.Bxc6 bxc6 15.Qxc6 Rb8 with a fully viable game according to an analysis from Tseitlin. Another retreat for the knight also occurred, with 11...dxc5 12.Qd5 Ng6 13.Bb5+ Bd7 14.Qxb7 O-O 15.Bxd7 Nxf4.

The same idea can be tried with the preparatory 11.Rc1, and after 11...O-O 12.c5!? dxc5 13.Qd5 Ng6 14.Bg3 White should be reminded that he has not finished his development with 14...Qf6! and a counterattack on b2. Playing Black, Svidler chose a different path with 11...b6 but his opponent Lesiège nevertheless sacrified the pawn with 12.c5!, when play continued 12...bxc5 13.b4 O-O 14.bxc5 Bb7 15.f3 and Svilder destroyed his own pawn structure with 15...dxc5!? in order to activate his pieces and make use of the d-file.

The most popular is 11.Be2 as White delays his queenside play until he has achieved castling. It also gives Black more time to organise defence on the queenside, e.g. 11...O-O 12.O-O b6! 13.Rac1 Bb7 14.Rfd1 a5 15.b4 Nd7 and the game is still balanced.
 * In a game Browne tried 11.Be2 b6 12.e4 but it did not bring the expected activity and he lost.
 * Koepcke tried 11.Be2 O-O 12.O-O b6 13.b4 Rd8!? 14.Qc3 and then his opponent Yermolinsky uncorked the cold-blooded 14...c5!, a surprising move that creates the disadvantage of a backward pawn in d6, but Lalic considers "Black's activity is sufficient to compensate for the weakness on d6 and in fact it is the white c4-pawn that could prove vulnerable one day."
 * Black can also let his opponent realise the push c4–c5 with 11.Be2 O-O 12.O-O b6 13.b4 Bb7 14.c5 and then seek counter-chances based on the possession of the d-file with 14...dxc5 15.bxc5 Rfd8.
 * Black can insert the preventive a7–a5 for the minor reason of delaying White's push b2–b4 and for the major reason of opening the a-file with a5xb4 once the push b2–b4 has been realised. The advantage for Black of opening the a-file is that white rooks cannot in the same time attack along the c-file and contest the a-file to the black rooks. So generally White abandons the a-file to concentrate on the attack along the c-file, and Black can use the a-file for its own purposes. For example a game Lavrov – Kaposztas saw the moves 11.Be2 O-O 12.O-O a5 13.Rac1 b6 14.Bg3 Bg7 15.Qc3 Rfe8 16.Rfd1 Nd7 17.b4 axb4 18.axb4 Nf6, with a double-edged position.

The line 6.Nbd2 Qe7 7.e3
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 Nc6 5.Nf3 Bb4+ 6.Nbd2 Qe7 7.e3

In this variation White tries to avoid the move a2–a3 in order to gain a tempo over the 7.a3 variation. After the standard moves 7...Ngxe5 8.Nxe5 Nxe5 9.Be2 followed by 10.O-O it is Black's last chance to exchange the Bb4 for the Nd2. The game will take an entirely different structure depending on whether Black gives up the bishop pair or tries to keep it.

Lalic thinks the strategies in which Black gives up the bishop pair (by exchanging its Bb4 for the Nd2) for nothing are a mistake. He does not like the strategy to retreat the Bb4 in d6 either, because they are too drawish. He recommends the strategy to retreat the bishop in c5, and keep it there thanks to the push a7–a5.

Black gives up the bishop pair
When Black goes for it with 10...Bxd2, he runs the risk to end up a tempo down over the 7.a3 variation and to be soon unable to meet White's positional threats on the queenside. White can avoid the push a2–a3 and continue with the standard plans of the 7.a3 variation. Tseitlin considers the main variation is 9.Be2 d6 10.O-O Bxd2 11.Qxd2 O-O 12.Rfd1 b6 13.b4 Bb7 14.c5 dxc5 15.bxc5 and then gives a line he analysed in which Black ends a pawn down but in a drawish position. Similarly, after the moves 9.Be2 Bxd2+ 10.Qxd2 d6 11.O-O O-O Lalic notices: "by exchanging so early on d2 and castling quickly Black has saved himself the worry of how to meet Nb3 and what to do with his king, but such simplistic logic is in no way going to guarantee him a comfortable game."

However, everything is not that bad for Black. First, to implement his plan White has to concentrate on development (9.Be2, 10.O-O) before he turns his attention to the queenside. That means Black has more time to organise his play than in the 7.a3 variation, notably to organise a blockade of the c5-square. Moreover, as White does not put immediate pressure, Black is not compelled to castle rapidly and he can keep his king in the centre for a longer time, or even castle queenside. Hence Lalic note that "White has not wasted time with a2–a3, but in fact it is not so easy to capitalise on this extra tempo."

A possibility for Black is to develop his light-square bishop rapidly, by prioritising the moves b7–b6 and Bc8–b7 against castling and d7–d6. Moskalenko does not like this plan on the basis of the game Solozhenkin – Stiazhkin (Leningrad 1990) where after 9...b6?! 10.O-O Bxd2 11.Qxd2 Bb7 White sacrificed a pawn with 12.c5! bxc5? 13.Qa5! d6 14.Bxe5! dxe5 15.Rfc1 and White stands better (the assessment of moves and of the final position are Moskalenko's). Lalic agrees with the assessment of the final position but does not think Black's ninth and twelfth moves are mistakes. Instead he thinks 13...d6? was the error and advises 13...Ng6! instead, with the example of the game Flear – Blatny that continued 14.Qxc7 Nxf4 15.Qxf4 O-O with a balanced position.

White is not compelled to sacrifice the c4 pawn at all. In the game Chernin – Blatny (Brno 1993) White calmly prepared the c4–c5 push with 9.Be2 b6 10.O-O Bxd2 11.Qxd2 Bb7 12.Rac1 d6 13.b4 Ng6 14.Bg3 and here according to Lalic Black went astray with 14...O-O?! 15.c5 that lets Black without a plan to counter White's attack on the queenside. Instead 14...h5!? can be suggested to attack White's kingside and force the exchange of the Bg3 against the Ng6.

In the game Gausel – Reite (Norwegian Team Championship 1991), after the same 9.Be2 b6 10.O-O Bxd2 11.Qxd2 Bb7 Black introduced a highly original plan by avoiding the natural advance d7–d6 and blocking a white c5-push in the most categoric way by realising a c5-push himself! The game went along 12.Qc3 f6 13.b4 c5!? Lalic was "deeply impressed by this plan, which really spoils all of White's fun". The c4-pawn is never allowed to advance, so that the Be2 is durably restricted. The Bf4 is obstructed by the Ne5, that cannot be easily removed. The weakness of the d7-pawn is not a worry as it can be protected by Bb7–c6 if necessary. After 14.b5 Lalic recommends 14...a6 to neutralise White's queenside initiative.

Black keeps the bishop pair
After 9.Be2 O-O 10.O-O Black can avoid the immediate exchange of his Bb4 against the Nd2 in several ways. The first one, resurrected and enriched by the grandmaster Pavel Blatny, is to exchange the Bb4 against the Bf4. This can be achieved via 10...Ng6 11.Bg3 (11.Bxc7?? d6 loses a piece) 11...Bd6 12.Bxd6 Qxd6. White still has possibilities to play for an advantage due to his advance of development, his space advantage on the queenside and the remote possibility to install his knight on the good square d5. For example the possible 13.Ne4 Qxd1? 14.Rfd1 d6 15.c5! dxc5 16.Nxc5 c6 17.Rac1 is uncomfortable for Black who is still underdevelopped. The game Stohl – Blatny (Prague 1996) shows the proper way for Black with 13.Ne4 Qe5 14.Nc3 b6 15.Qd5 and here Blatny introduced the novelty 15...Ba6! that breathed new life to this variation as Black has succeeded in equalising. After the tactical sequence 16.Qxe5 Nxe5 17.Nd5 c6 18.Nc7 Bxc4 19.Bxc4 Rac8! Black regains the sacrificed piece and the endgame is equal.

The other possibility for Black is to keep his Bb4 as long as possible, exchanging it against the white knight only in favourable circumstances. A couple of attempts have been done with this in mind, with subtle variations along the moves a7–a5 and b7–b6:
 * Against the mundane 10...d6 White can continue with 11.Nb3 (see diagram at right) to play on the queenside against the exposed Bb4. Black needs to fight for the dark squares b4 and c5, in order to avoid problems for its dark-squared bishop. After 11.Nb3 b6 12.a3 Bc5 13.Nxc5 bxc5 authors thought Black had an equal game with good play on the B-file, until the game Karpov – Short (first game in their 1992candidate match at Linares) where White continued with the immediate 14.b4! and Black cannot really take in b4 because the a7-pawn would remain weak. Hence the game continued with 14...Nd7 15.Bg4 and White is calling the shots. Another path for White is 11.Nb1 to recycle the knight on his ideal square d5. Lalic does not consider this as dangerous for Black, on the account of 11...a5 12.a3 Bc5 13.Nc3 Be6 14.b3 f5! with a strong control of the centre.
 * The same move 10...d6 can be played with the different idea 11.Nb3 d6. After the logical 12.a3 Bc5 13.Nxc5 dxc5 White has a pawn majority on the kingside that Black hopes to immobilise, and counterattack on the c4-pawn.The Ra8 can be quickly developed along the fifth line.
 * A third idea is the immediate 10...a5, to have the d6-square for the bishop, impeach the b2–b4 push and having the possibility a5–a4 if the white knight comes on b3. In the game Mikhalevski – Chabanon (Bad Endbach 1995), Black succeeded in keeping the bishop with 11.Nb3 a4 12.a3 Bd6 13.Nd4 Bc5 14.Nb5 d6 15.Nc3 Ng6 16.Bg3 f5 with dynamic play.

The sideline 6.Nbd2 f6
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 Nc6 5.Nf3 Bb4+ 6.Nbd2 f6

With 6...f6 7.exf6 Qxf6 Black tries to take advantage from the fact White has moved his dark-squared bishop away from the queenside, meaning the b2-pawn is left without protection. Lalic reckons that "although unsound at the highest level, this line has every chance of success as a surprise weapon at club level because White must play actively and accurately to secure the advantage."

One game saw the continuation 8.e3 Qxb2 9.Be2 d6 10.O-O O-O 11.Ne4 Nf6 12.Bd3 Bf5 13.Nxf6+ Qxf6 14.Rb1 Bc5 15.Ng5 Nb4! with Black trying to invade the d3-square. According to Lalic "fortunes could have turned either way." The correct plan for White was shown by Gleizerov who played 8.e3 Qxb2 9.Be2 d6 10.O-O O-O 11.Nb3 Qf6 12.c5! to open the a2–g8 diagonal that was weakened precisely by the gambit move 6...f6. The move 11.Nb3 is not only useful to support the c4–c5 push, but also to exchange the knight against Black's dark-squared bishop after a possible a2–a3 forcing the retreat Bb4–c5. As Lalic puts it, "I doubt if Black has a satisfactory answer to White's play in this game".

The sideline 5.Nbd2 d6
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 Bb4+ 5.Nbd2 d6

To reach this line Black has to avoid 4...Nc6 5.Nf3 Bb4+ and play immediately 4...Bb4+. Although this gambit has common themes with the other gambit 6...f6, it is basically more sound as Black does not weaken his kingdise (not opening the a2–g8 diagonal) and opens the way for his Bc8. After 6.exd6 Qf6 White can react to the attack on his Bf4 in several ways:
 * After 7.e3 the best for Black (according to Lalic) is 7...g5!, with the possible continuation 8.Bg3 h5 9.h4 Qxb2 (threatening 10...Bxd2+ winning a piece) 10.Ngf3 Bf5 threatening to win the exchange with 11...Bc2 12.Qc1 Ba3.
 * Also possible is 7.Bg3, with the hope of playing the advance e2–e4 in one go in a distant future. In one game play continued 7...Qxb2 8.Ngf3 Bf5 9.a3 Bxd6 10.Bxd6 cxd6 and Black was fine.
 * The best move is considered to be 7.Nh3 as it develops a piece and protects both the Bb4 and the f2-pawn. It also helps that the Bb4 is still guarding the Nd2, so that after 7...Qxb2? there is not the threat of winning the exchange (8...Bxd2+ would be answered by 9.Bxd2) and White can repell Black's attack with 8.Rb1 Qa3 9.Rb3 Qa5 10.dxc7 Nc6 11.a3! Be7 12.e3. Instead, Black must play energetically with 7...Nxf2 8.Kxf2 Bxh3 9.g3 Bxf1 10.dxc7!? Nc6 11.Rxf1 and here Lalic recommends 11...O-O 12.Kg2 Rfe8.

Alekhine variation 3...Ng4 4.e4
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.e4

This variation is named after Alekhine probably thanks to his wins in the games Alekhine – Rabinovic (Baden Baden, 1925) and Alekhine – Seitz (Hastings, 1926). Alekhine himself stated: "This is considered with good reason to be White's best system against the Budapest Gambit. White hands the pawn back, but in return gains control of d5. Over the next few moves, however, he has to play with extreme precision, since otherwise his central pawn position may become the object of a successful attack by Black."

White does not try to keep its material advantage (the e5-pawn) and concentrates on building a strong pawn centre, in order to get a space advantage. Notably a controversial point is whether the typical black manoeuvre Bf8–b4–xc3 is advantageous for Black (as it saddles White with doubled pawns) or for White (as it reinforces his centre). Lalic thinks both, considering 6...Bb4+ to be a bad move after 4...Nxe5 5.f4 Nec6 6.Nf3, but a good one after 4...Nxe5 5.f4 Nec6 6.Be3.

After 4.e4 Black has to do something about its Ng4 that is attacked by the Qd1. Apart from the main line, two minor variations have been tried:
 * with 4...h5?! Black does not want to get its gambit pawn back, and prefers to keep the Ng4 on its aggressive position. Thus White has to be careful not to fall in some traps like 5.Nf3? Bc5 or 5.f4?! Bc5 6.Nh3 Nc6 7.Be2? Qh4+. White does best to repell immediately the Ng4 with 5.Be2, after which the move h7–h5 is only a weakness and White has the advantage.


 * with 4...d6?! (sometimes called the "Balogh variation") Black continues in true gambit style, trying to develop rapidly its pieces, but the compensations are not sufficient. Here again, after 5.exd6 Bxd6 White needs to avoid some traps like 6.Nf3? Bc5! 7.Qxd8+ Kxd8 when Black regains the pawn with advantage. White continues with 6.Be2 to gain a tempo on the Ng4 when Black's only option to sustain an initiative is 6...f5 7.exf5 Qe7. Then White has a choice between chasing a slight positional advantage with 8.Nf3, or taking a piece with 8.c5! Bxc5 9.Qa4+ Nc6 10.Qxg4. In the later case, Tartakower and Euwe initially considered Black had enough compensation but more recent analysis proved them wrong.

The main line is 4...Nxe5 5.f4 when Black has an important choice to make about where to move its Ne5:
 * 5...Nec6 is considered to be the best
 * 5...Ng6 is probably playable
 * 5...Nbc6? 6.fxe5 Qh4+ (sometimes called the Wikstrom gambit), despite being called "highly regarded" by Lalic, is just a bad piece sacrifice with Black hoping for something like 7.g3? Qe4+ that wins a rook. As advocated by Nunn White can keep the material advantage with the funny 7.Kd2 Qf4+ 8.Kc3 Qxe5+ 9.Kd2 Qf4+ 10.Ke1 Qxe4+ 11.Qe2 when the black queen is pinned.

The 5...Nec6 line
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.e4 Nxe5 5.f4 Nec6

This line is sometimes called the "Abonyi variation". The Knight on c6 is safer than on g6, and can be part of a general strategy on the dark squares. It can go on d4 while the other Knight can go on c5 via a6 or d7.

After 6.Nf3 Bc5 White has difficulties to castle short, because the plan to exchange the dark-squared bishops with Bd3/Qe2/Be3 can be met by Bg4/Nd4 in order to muddy the waters. Therefore, as Lalic points out: "White can no longer catle kingside and will usually have to go the other way. However, this is rather slow and gives Black time to try and undermine the white centre. To this end Bc8–g4 often comes in handy, in order to pin the white knight on f3 against the white queen. Note that Black should wait until his opponent has wasted a tempo with Qe2."

A possible continuation is 6.Nf3 Bc5 7.Nc3 d6 8.f5 ("!?" Lalic) 8...Nd7 9.Bg5 f6 10.Bf4 and here Black has to prepare the exchange of the Bc5 against the Nc3 with 10...Bb4 ("!" Lalic), because a White knight on the d5-square would be too strong now that it cannot be challenged by Bc8–e6 and it can continue with Nd5–f4–e6 in the long run. A slower course of action is 6.Nf3 Bc5 7.Nc3 d6 8.Bd3 O-O 9.Qe2 Bg4 ("!" Lalic) 10.Be3 Na6 11.O-O-O f6 with a typical game of opposite castles. White cannot, however, afford the luxury of being too slow, e.g. after 6.Nf3 Bc5 7.Nc3 d6 8.Bd3 O-O 9.h3 ("?!" Lalic) 9...Re8 it is already time for White to seek a simplification with 10.Qe2 Nd4 11.Nxd4 Bxd4 12.Be3 Qh4+ 13.Qf2, otherwise Black would soon have strong pressure in the centre thanks to the semi-open e-file.

Another try is 6.a3 but it creates a significant weakness in b3 and it is rather slow. For example after the possible 6...a5 7.Be3 Na6 8.Bd3 Bc5 9.Qd2 d6 10.Nf3 O-O 11.Nc3 Bxe3 12.Qxe3 Nc5 13.O-O Re8 14.Bc2 a4 Borik has shown that the possibility to attack the c4-pawn with Be6/Na5 gives sufficient play to Black. Note that Black is not compelled to reply to 6.a3 with 6...a5, and can also treat a2–a3 as a mere loss of tempo by switching to another development like d6/g6/Bg7/O-O with equality. As Lalic puts it: "[I] believe that Black should now opt for the plan of fianchettoing his dark-squared bishop. The black bishop will be excellently posted on g7 and Black's kingside will also be more robust against White's eventual kingside attack. Psychologically, if White has 'all the time in the world' for such moves as 6.a3, it makes sense to divert the bishop to another diagonal instead of 'respecting' White's move with 6...a5."

White has also experimented a plan with a quick queen raid on the kingside, involving moves like Nc3/Qh5/Bd3/Nd5. This plan was first tried in a game of Alekhine against Gilg and after 6.a3 a5 7.Nc3 Bc5 8.Nd5 O-O 9.Bd3 d6 10.Qh5 Nd7 ("?" Tseitlin) 11.Nf3 h6 12.b4 ("!" Alekhine) 12...axb4 13.Bb2 bxa3 14.Bc3 White has a strong initiative. One year later Gilg was playing White and tried to repeat Alekhine's success in a game against Vajda, but the latter improved with 10...Nd4 ("!" Tseitlin) and won. This plan can also be tried without the advance a2–a3, e.g. 6.Nc3 Bc5 7.Qh5 d6 8.Bd3 Nd7 9.Nf3 Nf6 10.Qh4 and here Lalic recommends 10...O-O.

White takes the diagonal with 6.Be3
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.e4 Nxe5 5.f4 Nec6 6.Be3

The continuation 6.Be3 controls the a7–g1 diagonal, takes the good c5-square from the Bf8, and is considered to be the best reply. If Black wants to contest that he can try 6...Na6 to continue with 7...Nc5, but most of the games continue with 6...Bb4+. Here the best reply for White is controversial. While Borik does not express a preference, Alekhine strongly recommends 7.Nc3 (awarded a "!"): "Much stronger than 7.Nd2, for with the knight threatening to jump to d5, Black will sooner or later be forced to exchange his important dark-squared bishop for it. The doubling of the c-pawns in these circumstances is not something White should fear." Tseitlin agrees, stating that "after 7.Nd2 Black has no difficulty at all". On the other hand, Lalic thinks 7.Nd2 (awarded a "!") is more accurate: "White avoids the doubled c-pawns that are likely to occur after 7.Nc3, and this knight can latter be deployed via the b3-square. The Russian grandmaster Rustem Dautov [...] is the maestro of this variation with many impressive victories under his belt."

Actually Tseitlin's opinion on 7.Nd2 is based on the game Nikolić – Lev (Groningen 1985–86), which continued 7...Qe7 8.a3 ("?" Tseitlin) 8...Qxe4+ ("!" Tseitlin) 9.Qf3 Bxd2+ 10.Kxd2 Qxf3 and White is a pawn up. But what Tseitlin considers a white blunder is called a gambit by Lalic, who gives 7.Nd2 Qe7 8.a3 ("!" Lalic) 8...Qxe4 ("it is probably wise to decline the gambit", Lalic) 9.Kf2 Bxd2 10.Qxd2 O-O 11.Nf3 d6 12.Re1 Qf5 13.Bd3 Qa5 14.b4 Qh5 and White won.

After 7.Nc3 Black has the interesting zwischenzug 7...Qh4+ ("!" Borik) 8.g3 Bxc3+ 9.bxc3 Qe7 so that the diagonal a8–h1 is weakened before Black places his Bc8 on the b7-square. The queen on the e7-square is well placed to pressure the e4-pawn. However, as all Black's pieces are on the queenside, continuing with pawn pushes like f7–f5 is probably too weakening, as Alekhine demonstrated in his game against Seitz in 1925. So Black does best to attack with pieces, possibly with the setup b6/Nc5/Bb7/O-O-O. In that case Tseitlin considers that with a knight on c5 the move d7–d6 should be avoided if Black has to respond to the capture Bxc5 by dxc5, because the white pawns in e4 and f4 would have too much leeway.

After 7.Nd2 the pressure on the e4-pawn with 7...Qe7 does not live long after 8.a3 Bc5 9.Bxc5 Qxc5 10.Qf3 and now 10...Nd4 would be premature so that Lalic recommends 10...a5. The introduction of the intermediate 7...Qh4+ 8.g3 Qe7 does not change the picture for Lalic, as after 9.Bg2 Na6 10.a3 Bc5 11.Bxc5 Nxc5 12.b4 Ne6 the bishop was well placed in g2 and Black experienced difficulties to develop his own Bc8. But Lalic does not mention the game Pomar – Heidenfeld cited by Borik, in which Black played the advance a7–a5 to avoid the white advance b2–b4, hence reaching equality after 9.Bg2 a5 10.Ne2 Na6 11.O-O d6 12.Nb3 Bg4 13.h3 Bxe2 14.Qxe2 a4. Instead, he recommends 7...d6 8.Nf3 O-O 9.Bd3 and now the same development as in Pomar's game: "9...a5 and 10...Na6 deserves attention, when White's movements on the queenside are more restricted and the black knight will be able to settle on the c5-square without being kicked by the thematic b2–b4. It may appear that we have reached the same position elaborated in previous games a tempo down for Black, since he has committed hi bishop to b4 and will later drop back to the c5-square instead of heading there at once. However, the white knight is less actively placed on d2 and in fact this fully compensates Black for the slight loss of time."

The 5...Ng6 line
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.e4 Nxe5 5.f4 Ng6

The Knight on g6 puts the f4-pawn under pressure, but may be embarrassed and lose a tempo if White pushes f4–f5. Now 6.a3, an attempt to take all squares from the Bb8 by continuing with b2–b4 or Bc1–e3, does not work that fine after 6...Bc5! 7.b4?! Bxg1! 8.Rxg1 O-O! 9.Qf3 d6 10.g4 a5 11.b5 Nd7 12.Ra2 Nc5 when Black's superior pawn structure and well-positioned Nc5 gives him the advantage. That leaves White with the choice between 6.Nf3 and 6.Be3.

The move 6.Nf3 controls the e5-square in order to prepare the push f4–f5. Unlike after 5...Nec6, White does not have to fear 6...Bc5 ("?!" Lalic), which runs into difficulties after 7.f5! Nh4 8.Ng5 ("!" Lalic), when the Black knight is already in danger of being lost to Qd1–g4 or Qd1–h5. Thus Black must react quickly with 6...Bb4+ 7.Nc3 when he can adopt a normal setup with d6/O-O/Nc6/b6 or act boldly with 7...Qf6 threatening both the Nc3 and the f4-pawn. One point in favour of 7...Qf6 is that after 8.e5 Qb6 the black queen prevents White to castle short and is well placed if White castles long.

The move 6.Be3 takes the a7–g1 diagonal from Black's Bf8 and may in some lines prepare the long castle. After the mandatory 6...Bb4+, during several moves Black will have the choice between aggressive and quiet continuations:
 * White can opt for 7.Nd2 to avoid having doubled pawns, but he must be prepared to sacrifice a pawn after 7...Qe7 8.Kf2 ("!?" Lalic) 8...Bxd2 9.Qxd2 Qxe4 10.Bd3 with piece activity for the pawn deficit, because the normal defense 8.Bd3 ("?" Lalic) runs into 8...Qd6 ("!" Lalic) and both the Bd3 and the f4-pawn are attacked.
 * White does not need, however, to bother about the doubled pawns and after 7.Nc3 Bxc3+ 8.bxc3 Black can choose the quiet 8...b6 ("!?" Borik) followed with a normal development like d6/O-O/Bb7/Nd7/Re8/Nc5.
 * An ultra-aggressive continuation for Black is 7.Nc3 Bxc3+ 8.bxc3 Qe7 9.Bd3 f5 ("!?" Lalic) 10.Qc2 fxe4 11.Bxe4 when Black can free his play with the pseudo-sacrifice 11...Nxf4 12.Bxf4 d5 13.cxd5 Bf5 regaining the piece. Lalic continues this line by 14.Qa4+ b5! 15.Qxb5+ c6 "with great complications".
 * Lalic proposes Black with a middle way, after 7.Nc3 Bxc3+ 8.bxc3 Qe7 9.Bd3 O-O 10.Qd2 and only now that Black has his king safe shall he unleash 10...f5!?, when "it is not so easy for White to meet [10...f5] as the two main responses, 11.e5 and 11.exf5, allow Black promising chances with 11...d6 and 11...Nxf4 respectively".

The 4.e3 line
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.e3

After 4.e3 Nxe5 White has no interest in playing 5.Nf3 Nxf3 6.Qxf3 Nc6 and Black has equality, so he ought to continue with 5.Nh3 when this knight starts the journey Ng1–h3–f4–d5 in order to reach its ideal square. Black has tried to prevent White's idea by the suitably strange move 5...Ng6, taking the f4-square from the Nh3. Then White can develop along various setups, the most active being 6.Qh5 with the possibility Nh3–g5 in store to recycle the knight towards a more central position.

Black can also ignore White's intentions and concentrate on his own play by placing the Nb8 on c5, in order to put pressure on the d3-square. After 5...g6 6.Nf4 Bg7 7.Be2 O-O 8.O-O d6 9.Nc3 Nbd7 10.Qd2 a5 11.b3 Nc5 the position of Black's knights is secured and Black's position is similar to the Leningrad variation of the Dutch Defence (once he has played f7–f5). White has no reason, however, to abandon the a1–h8 diagonal to Black, and he can try 5...g6 6.Bd2 d6 7.Nf4 Bg7 8.Bc3 O-O 9.Be2 Nbd7 10.Nd2 b6 and in one game White seized a minimal edge.

The 4.e6 line
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.e6

This is generally an attempt by White to avoid complications and head for a draw. Indeed, after 4...dxe6 5.Qxd8+ Kxd8 the position is equal, Black's loss of the right to castle being of no great importance since queens have been traded. If Black wants to avoid this early endgame, he can try 4...Bb4+: The capture 4...fxe6 is also playable and avoids the endgame, at the price of a weakened protection for the Black king.
 * 5.Nc3 Bxc3+ 6.bxc3 dxe6 offers the exchange of queens in a more favourable position for Black, as the white queenside pawns are isolated and doubled. The alternative 7.Qd4 e5 8.Qe4 f5 9.Qc2 O-O gives a lively game.
 * 5.Bd2 Qf6!? with dynamic play on f2 and b2.

The 4.Qd5 line
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Qd5

After 4...Nc6 White should seize the last opportunity to get back in calm waters with 5.Bf4 Bb4+ 6.Nc3 which will soon transpose into the Rubinstein line 1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 Nc6 5.Nf3 Bb4+ 6.Nc3 Bxc3+ 7.bxc3 Qe7 8.Qd5.

Alternatively White can try 5.Nf3 with similar themes as the 4.Qd4 variation, Black aiming for rapid activity at the cost of a pawn with 5...d6. White achieves nothing with the zwischenzug 6.Bg5 because after 6...Be7 7.Bxe7 Nxe7 8.Qe4 dxe5 he cannot get its pawn back because of the "Schlechter trap" 9.Nxe5? Qd1+! 10.Kxd1 Nxf2+ with clear advantage to Black. So White has to accept the gambit with 6.exd6 Be6 7.d7+ Bxd7 when Black's lead in development compensates for the pawn.

The greedy 5.f4 is not recommended, as it combines the disadvantages of the early queen development and of the weakening of the a7–g1 diagonal by f4, with similar themes to those in the 4.f4?! variation given below.

The 4.Qd4 line
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Qd4

The move 4.Qd4 is natural as it protects the e5-pawn and attacks the Ng4. However, "the problem for White in the Budapest is that natural moves often lead to disaster". Black has a choice between:
 * the calm 4...h5, aiming to recover the pawn a bit later.
 * the gambit 4...d6 aiming for dynamic piece play,

The loss of tempo implied in 4...h5 is not serious as Black will regain a tempo against the white queen when Nbc6 is played. Moreover after 5.Nf3 Nc6 6.Qd5 Bb4+ 7.Nc3 Qe7 8.Bf4 the game reaches a position similar to the ones in the Rubinstein variation (with the manoeuvre Qe7–a3 to come), when the extra move h7–h5 is useful as it gives the Ng4 a retreat square on h6, and may prepare a raid g7–g5/h5–h4 against the Bf4 in some variations.

More common is the gambit 4...d6 5.exd6, when after 5...Bxd6 White cannot play 6.Qxg7?? because 6...Be5 7.Qg5 Qxg5 8.Bxg5 Bxb2 wins material. Thus for the sacrificed pawn Black has a lead in development (two pieces out) and will gain further tempi by attacking the exposed White queen. However, White can complicate Black's development with 6.Nf3 O-O 7.Bg5!? in order to force the Black queen to an unfavourable square. Unfortunately for White, Black can avoid this manoeuvre with a different move order, 5...Nc6!? 6.Qd1 Bxd6, when 7.Nf3?? is not possible anymore because of 7...Nxf2! 8.Kxf2 Bg3+ winning the queen. Hence White must develop more quietly with moves like Nc3/Nf3/e3/Be2, allowing Black to find active positions for his pieces with O-O/Be6/Qe7/Rfd8 and prepare several sacrificial ideas on e3 or f2, with excellent attacking possibilities.

The 4.f4?! line
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.f4?!

This is considered weak because White neglects development and weakens the a7–g1 diagonal. Black immediately exploits this with 4...Bc5, which threatens a fork in f2 and forbids White's castling. Then after 5.e3 Black has a pleasant choice between regaining the pawn immediately with 5...Nxe3 or gambitting another pawn with 5...d6 to open the centre against White's king, when play may continue 6.exd6 O-O 7.Nc3 Bxe3 8.Bxe3 Nxe3 9.Qd2 Re8 10.Kf2 and Black has a nice attack. So White may prefer to play 5.Nh3 when Black can also get some active play by gambiting another pawn with d7–d6, now or later. For example after 5...O-O 6.Nc3 d6 7.exd6 cxd6 Black has good squares for all its pieces, while White's castling is seriously delayed.

Fajarowicz variation 3...Ne4
1.d4 Nf6 2.c4 e5 3.dxe5 Ne4

The Fajarowicz variation is said to have its origins in the chess circles from Leipzig, with the first important game being H.Steiner – Fajarowicz at the Wiesbaden tournament in 1928.

Black makes no immediate effort to regain the gambit pawn, preferring to concentrate on activee piece play. As the game develops, White will have to avoid several tactical pitfalls, in particular a Bb4+ at an annoying moment; a Qf6 doing a double attack on b2 and f2; (after 1...d6 2.exd6 Bxd6) the pseudo-sacrifice 3...Nxf2 4.Kxf2 Bg3+ and 5...Qxd1, winning White's queen for two minor pieces; and, once White has played e3, a concerted attack on the d3 square with the setup Nc5+Bf5+Nb4.

According to Borik, the best moves for both players are 4.Nf3 Bb4+ 5.Nd2 Nc6 6.a3 Nxd2 7.Nxd2 Bf8 when it is difficult for Black to justify his pawn sacrifice. The variation 4.a3 also gives Black some headache, disallowing the check on b4 and preparing to attack the knight with Qc2. The response 4...Qh4?!, introduced in O'Kelly–Bisguier (1969) is dubious after 5.g3 Qh5 6.Nf3 Nc6 7.Qc2! Less good is the immediate 4.Qc2, which gives a tactical (after 4...d5) or positional (after 4...Bb4+) struggle, with good play for Black in the latter case.

Fajarowicz variation 3...Ne4, line 4.a3
1.d4 Nf6 2.c4 e5 3.dxe5 Ne4 4.a3

The move 4.a3 allows White to avoid the annoying bishop check on b4, the also annoying knight jump to b4, and prepares Qc2 to undermine Black's knight. Both Lalic and de Firmian consider it to be White's best move, with de Firmian assessing it as leading to a large advantage for White. Black has several possible answers:


 * De Firmian gives 4...Nc6 as the main move, Black hoping for White to help his development with 5.Nf3 d6 6.exd6?! Bxd6 when Black gets short-term hopes of winning the white queen (e.g. 7.g3?? Nxf2! 8.Kxf2 Bxg3+ ) and long-term hopes of an attack. A game saw 7.e3 Bf5 8.Be2 Qf6 9.O-O O-O-O 10.Qb3 g5! with "a kingside attack that has every chance of success due to White's dormant queenside". Another try was 7.Nbd2 Bf5 8.g3?! Bc5! 9.e3 Qf6 10.Bg2 O-O-O 11.O-O h5! with a "potent kingside attack". Much better for White is the continuation 5.Nf3 d6 6.Qc2! (considered by Lalic to be "the most ambitious move and one that is highly annoying from Black's point of view, as the knight on e4 is forced to declare itself" ) 6...Bf5 (awared a "?!" by Lalic) 7.Nc3! Nxf2 8.Qxf5 Nxh1 9.e6 fxe6 10.Qxe6+ Qe7 11.Qd5 h6 12.g3 g5 13.Bg2, when White had a large advantage in the game Reshevsky – Bisguier (New York 1955). Instead, after 5.Nf3 d6 6.Qc2 d5 7.e3 Lalic points out the untried 7...Bg4!? with the possible continuation 8.cxd5 Qxd5 9.Bc4 Qa5+ 10.b4 Bxb4+ 11.axb4 Qxa1 12.Qxe4 Bxf3 13.gxf3 Qxe5.


 * The theoretical novelty 4...Qh4 (awarded a "?!" by Lalic) was played in the game O'Kelly – Bisguier (San Juan 1969) and Black succeeded in achieving a quick draw, but later developments have called the move into question as Black's development will be lacking. After 5.g3 Qh5 6.Nf3 Nc6 (so far as in O'Kelly – Bisguier), White can play 7.Qc2! attacking the maverick knight. Borik then gives "7...Qf5! (threatening ...Nxg3)", but in fact 7...Qf5?? is refuted by 8.Nbd2! Nxg3 9.e4! and White wins. White has also reached successful prospects by returning the pawn for development, e.g. 5.g3 Qh5 6.Bg2 Qxe5 7.Qc2 Nf6 8.Nf3 Qh5 9.Nc3 Be7 10.h3 c6 11.e4 d6 12.b4 Nfd7 13.Ne2! with the threat 14.Nf4 winning the white queen.


 * Another possibility is 4...d6, hoping for the tactical trick 5.exd6 Bxd6 6.Nf3?? Nxf2! 7.Kxf2? Bg3+ and Black wins White's queen. Stronger is 5.Qc2, when 5...Nc5 is advised as 5...Bf5 is strongly met by 6.Nc3! (playing on the pin of the e4-knight, as 6...Ng3? is rebuffed by 7.e4! ) and 5...d5 would lose a tempo as the d-pawn has reached the d5-square in two moves instead of one. The less critical 5.Nf3 is also possible.


 * A fourth line for Black is 4...b6 (awarded a "!?" by Lalic, who recommends it as the best answer to 4.a3), which is sometimes called the Bonsdorf variation. White cannot win a piece with 5.Qd5?! because of the usual trick 5...Nc5! 6.Qxa8? Bb7 7.Qxa7 Nc6, trapping White's queen. Another point is that Qd1–c2, so effective in most of the other lines, can be met by Bc8–b7. After 5.Nd2 Bb7 6.Qc2, Lalic gives 6...Nxd2 7.Bxd2 a5!, when the black bishops will be excellently placed on b7 and c5. Lalic recommends 6.Nf3 instead, while MCO-15 continues by 5.Nf3 Bb7 6.Nbd2 Qe7 7.Qc2 with a large advantage for White in the game Hillarp Persson – Romero Holmes (Bali Stars 2003).


 * The slow 4...a5 (awarded a "?!" by Lalic) is a luxury that Black cannot afford, e.g. 5.Nf3 Nc6 6.Qc2 d5 7.e3 Be6 8.Be2 f6 9.exf6 Qxf6 10.O-O Nc5 as in the game Yrjola – Bellon Lopez (Helsinki 1991).

Fajarowicz variation 3...Ne4, line 4.Nf3
1.d4 Nf6 2.c4 e5 3.dxe5 Ne4 4.Nf3

This hinders the manoeuvre Qd8–h4–h5, although recent analysis suggests that White need not fear that. Tseitlin considers 4...Bb4+ to be the best reply, but the most common move is still 4...Nc6 and both moves often transposes anyway. After the continuation 5.Nbd2 Bb4 6.a3 Nxd2 7.Bxd2 Bxd2+ 8.Qxd2 Qe7 9.Qc3 much will depend on whether Black can get his pawn back or not, and in what conditions. Tseitlin gives a line starting by 9...O-O as leading to a White advantage, but it is not clear that Black's king belongs to the kingside, as Lalic explains: "The plan of castling queenside enables Black to play for g7–g5, intending to undermine the defence of the e-pawn or simply to launch an attack if White has still had the courage to castle kingside."

Black has also tried 5...Nc5, in order to let the Nd2 on its bad square where it blocks the Bc1. White can dominate the light squares with the development Bf1–g2, and after 6.g3 d6 7.exd6 Bxd6 8.Bg2 O-O 9.O-O Qf6 10.Nb3 Be6 11.Nxc5 Bxc5 12.Qa4 Bg4! Black retains good attacking possibilities for the gambit pawn. Another idea for Black is to castle long, with 6.g3 d6 7.exd6 Qxd6 8.Bg2 Bf5 9.O-O O-O-O 10.a3 and now the move 10...Qf6 is essential to hinder the dangerous advance b2–b4. White can also opt for a more classical development with 6.a3 (threatening 7.b4) 6...Qe7 7.e3 Nxe5 8.Qc2 a5 9.b3 b6 with roughly equal chances.

Better than 5.Nbd2 is the preparatory move 5.a3!, hindering any Bf8–b4+ or Nc6–b4 idea that are very useful to Black in the 4.Qc2 variation. Now Black has to do something about the Qd1–c2 threat. He can try 5...d6 hoping to attract his opponent into something like 6.exd6 Bxd6 7.Nbd2 Bf5 8.e3 Qf6 9.Nxe4 Bxe4 10.Bd3 where Black retains some play. But White should not oblige and must play the strongest 6.Qc2 so that after the sharp 6...Bf5 7.Nc3 Nxf2 8.Qxf5 Nxh1 Black will not be able to save his Nh1 and White has the advantage. Even if Black reacts with the more prudent 6...Nc5 7.b4 Ne6 8.Bb2 dxe5 9.e3 f6 10.Bd3 g6 11.Nc3 Bg7 White has the initiative and Black can only hope to gradually neutralise White's strong pressure.

Therefore Black does best to include 4...Bb4+ which Tseitlin considers "the simplest and most reliable course", as White then has to choose between different difficulties. After 5.Bd2 Nxd2 6.Nbxd2 Nc6 7.a3 Bxd2+ 8.Qxd2 Qe7 9.Qc3 it seems White has everything covered, but Borik thinks Black will eventually be able to regain his pawn with the plan b6/Bb7/O-O-O/Rde8/g5/g4, with an initiative on the kingside. Tseitlin does not agree and prefers the continuation 7...Bf8! (instead of 7...Bxd2+) 8.Qc2 g6 9.Qc3 Bg7 so that "Black not only makes sure of recovering the gambit pawn, he also preserves the advantage of the bishop pair". Black's chances are to be preferred.

So it is better for White to keep the bishop with 5.Nbd2 Nc6 6.a3 and now Black can easily get confused by the move-order. After the natural 6...Nxd2 7.Bxd2 Bxd2+ 8.Qxd2 Qe7 9.Qc3 the game has transposed in the same position as after 5.Bd2, but White can also try 6...Nxd2 7.axb4! Nxf3+ 8.gxf3 Nxe5 9.Rg1 Qe7 10.Ra3! with a strong initiative. White can even retain his bishop with 6...Nxd2 7.Nxd2 and now Borik recommends 7...Bf8 with difficult play for Black as he is not certain to gain his pawn back. To avoid these possibilities Lalic advises the move-order 6...Bxd2+ 7.Bxd2 Nxd2 8.Qxd2 Qe7, but does not mention the possibility of White answering 6...Bxd2+ with 7.Nxd2. A possible improvement for Black would be 5...d5 when Tseitlin sees sufficient compensation for the pawn in all lines.

Fajarowicz variation 3...Ne4, line 4.Qc2
1.d4 Nf6 2.c4 e5 3.dxe5 Ne4 4.Qc2

This line is sometimes called the Steiner variation. White immediately attacks the Ne4, but takes care not to put the queen on a square where Black could attack it while developing (as would be the case after 4.Qd3 or 4.Qd4). Now any retreat by the Ne4 would mean that Black loses his advance in development, in which case he no longer has any compensation for the sacrificed pawn. Thus Black must continue to develop while trying to keep the Ne4 on its square, but that is by no means easy. Borik thinks 4.Qc2 is the one "that gives Black the most problems to solve", but Lalic does not agree at all, stating that the reply "4...Bb4+ [....] followed by d7–d5 ensures Black rapid development and plenty of counterplay, it is for this reason that 4.Qc2 is not on the danger list".

The reply 4...d5 protects the Ne4 and opens the way for the Bc8. Now various natural moves for White are not satisfactory: Therefore White's best is 5.exd6 so that the Ne4 remains under attack. As before, removing the knight from its outpost with 5...Nxd6 would mean failure, so Black continues to develop with 5...Bf5, in the same time creating the threat 6...Ng3.
 * 5.cxd5 allows Black to develop its queen with 5...Qd5, when White is not able to keep the e5-pawn and parry the various threats on the a5–e1 diagonal on the same time, for example 6.Nc3 Nxc3 7.Qxc3 Nc6 with the double threat Qxe5 and Bb4, or 6.Nd2 Bb4 7.Ngf3 Nc6 8.a3 Bxd2+ 9.Bxd2 Nxd2 10.Qxd2 Qxd2+ 11.Kxd2 Bg4 followed by O-O-O and Rhe8.
 * 5.Nf3? Bf5 (threatening 6...Ng3) 6.Qa4+ Nc6 7.Be3 Bb4+ 8.Nbd2 d4! and White has more and more problems to solve with g7–g5 to come.

Now again White has a lot of opportunities to go astray: Thus White has a lot of difficulties to get out of the pin, but on the other hand the Ne4 is also under a kind of pin as the Bf5 is not protected. Hence the best for White is the paradoxical 6.Nc3! when White keeps his queen under the threat of the Bf5 but develops his pieces and attacks the Ne4 once more. Now the e4-knight has only two discoveries that protect the Bf5, but 6...Ng3 fails to the tactical 7.Qa4+ Bd7 8.dxc7 Qxc7 9.Nb5! and White wins. Thus Black has only 6...Nxd6 to keep the initiative.
 * 6.dxc7 is too greedy, giving an important tempo and opening the d-file for the Ra8. Black continues with Qxc7, Nc6 and O-O-O, then depending on the circumstances he can create pressure on the d3-square with Nc5 and Nb4.
 * 6.Qa4+ and 6.Qb3 lose at least two tempi as the white queen will again be under attack when Black plays Ne4–c5. Black easily develops his pieces with Nc6, Bxd6 and an attack along the central columns.

Now a retreat with the white queen would give a development advantage to Black, so White uses the fact that his sixth move has given him enough control of the e4-square to play 7.e4!, preparing the development of the Bf1 and attacking the Bf5. Unfortunately for Black any reasonable defence like 7...Qe7 or 7...Bg6 would give White the time to catch up in development, and remain a pawn up. Thus Black's best option is the piece sacrifice 7...Nxe4 to grab a pawn and tempt White into a fire of tactical pressure.

The acceptance of the sacrifice with 8.Nxe4 gives Black enough play for the piece, e.g. after 8...Bb4+ 9.Ke2 Nc6 10.Be3 Qe7 11.f3 O-O-O. White does best to give up an exchange and continue his development with 8.Bd3! when after the possible 8...Nxf2 9.Bxf5 Nxh1 10.Nf3 White has an enormous lead of development for his material investment. White's position is to be preferred.

Less committal is 4...Bb4+, intending to pin the white pieces before deciding what to do with the Ne4. White cannot reply 5.Bd2 as he would lose the bishop pair and Black would easily regain the e5-pawn with Nc6/Qe7/O-O/Re8. After 5.Nd2 this knight is misplaced and blocks the Bc1, so Black can open the game with 5...d5 in favourable circumstances, when White can continue in several directions:
 * 6.cxd5 will probably transpose into the 4.Qc2 d5 5.cxd5 variation, which is not very good as Black develops his queen with tempo.
 * 6.e3 is a bit passive, e.g. 6...Bf5 7.Bd3 Qg5! 8.g3 Nd7 9.Ngf3 and here Borik recommends 9...Qh5 with a good attack, a possibility that is also endorsed by Tseitlin.
 * 6.Nf3 was tried in 1987 for the first time but did not bring any luck to its inventor.
 * 6.exd5 is best, when after 6...Bb5 White shall take care of removing the pin on the Nd2 thanks to 7.a3 Bxd2+ 8.Bxd2 Qxd6. Black has enough compensation for the pawn with his active Ne4 and Bf5.

The other possibility for White is 5.Nc3 so that the Bc1 is not blocked. Black continues with 5...d5 when White should avoid the natural continuation 6.cxd5?! Qxd5 7.Bd2 Qxd2+ 8.Qxd2 Nxd2 9.Kxd2 Nc6 because he has no satisfactory way to save the e5-pawn (e.g. 10.Nf3?! Bg4 11.e3 O-O-O+ 12.Kc2 Bf5+ etc.) so that Black gets a favourable endgame. After the better 6.exd6 (instead of 6.cxd5?!) 6...Bf5 7.Bd2 Nxd6 8.e4 Bxc3 9.Bxc3 Bxe4 Black has regained his pawn but White has the bishop pair and possibilities of an attack on the kingside. Instead of 8.e4 White can also try 8.Qb3 Nc6 9.e3 Qe7 10.Nf3 O-O-O but Black has good counterplay for the pawn.

Fajarowicz variation 3...Ne4, other fourth moves
Apart from the main moves listed above, the other possible fourth moves do not promise much for White.

The moves 4.Qd3 and 4.Qd4 seem to gain a tempo by attacking the Ne4, but after 4...Nc5 followed by 5...Nc6 Black gets his tempo back and the queen remains misplaced. Then Black can develop with d6 its Bb8 with the pawn exchange d7–d6, and then setup an attack on the light squares c2 and d3 with moves like Bf5 and Nb4. It is important that Black gets the move d7–d6 soon enough, as he must be able to answer a possible Bc1–g5 with Qd8–d7. In that way he avoids an exchange of pieces and the queen can still play on the light squares via the f5-square. If White gets his queen on g3, Black can protect his g7-pawn with Nc5–e6 when the white queen will soon reveal to be misplaced.

The move 4.Qd5 seems better as the queen cannot readily be attacked by the black knights. Lalic awards it a "?!" on the basis of the game Ullrich – Richter (Bad Elster 1937) that continued 4...Nc5 5.b4 Ne6 6.a3 a5 7.b5 d6 and "Black obtained a strong initiative [...] on account of the weakened white queenside". But Borik considers 4...Nc5 to be a slight mistake because White will have the move Bc1–g5 before Black plays d7–d6, for example 4...Nc5? 5.Nf3 Nc6 6.Bg5! and Black cannot avoid the unfavourable exchange of dark-squared bishops. Instead, Borik recommends 4...Bb4+ (a move considered as "playable" by Lalic) so that White has the annoying choice between giving his bishop pair with 5.Bd2, wrecking his pawn structure with 5.Nc3, or blocking his own bishop with 5.Nd2. In that latter case, an important tactical finess is that after the possible 5...Nc5 6.a3 Bxd2+ 7.Bxd2 b6! White cannot take the black rook because of 8.Qxa8? Bb7 9.Qxa7 Nc6 that wins the white queen. Thus Black can freely develop its queenside, harass the white queen and later regain the e5-pawn.

Lalic also mentions 4.g3 as "an ugly looking but nonetheless satisfactory experiment" in the game Schandorff – Conquest (Torsharn 1997).

The move 4.Nd2 obstructs the Bc1 and misplaces the knight. For example after 4...Nc5 5.b4 Ne6 6.a3 a5! the attacks on the b4-pawn force White to give away the c5-square with 7.b5. Then Black has a good game as he can install a knight on the strongpost c5 and then concentrate on regaining the e5-pawn.

The cooperative 4.Nc3 is inferior, since Black can simply respond with 4...Nxc3 5.bxc3 b6!, fixing White's weaknesses and intending to regain the gambit pawn later. If Black does not want a positional game he can go for a more dynamic struggle by 4...Bb4 as after 5.Qc2 the game has transposed in the 4.Qc2 Bb4+ 5.Nc3 variation.

Declining the gambit
Declining the gambit is almost never seen in master play because it promises White equality at best.

After 3.d5?! Bc5 White has prematurely blocked the central position, giving the a7–g1 diagonal to Black for his bishop. For example after 4.Nc3 d6 5.e4 c6 6.Bd3 cxd5 7.cxd5 a6 8.Nf3 Nbd7 9.O-O O-O Black is better. In this variation Black can either play on the queenside with a plan like b5/Nb6/Bd7, or on the kingside with a plan like Ne8/g6/Ng7/f5. In this line, 4.Bg5?? is a notorious blunder, giving Black a winning advantage after either 4..Bxf2+ 5.Kxf2 Ng4+ 6.Ke1 Qxg5, or 4...Ne4 (hoping for 5.Bxd8?? Bxf2#, as in F. Arnold – M. Hanauer, Philadelphia 1936) 5.Be3 Bxe3 6.fxe3 Qh4+.

After 3.e3?! exd4 4.exd4 Black can transpose into a line of the exchange variation of the French defence with 4...d5. He can also wait a bit before committing to d7–d5, and develop rapidly with 4...Bb4+ 5.Bd2 Bxd2+ 6.Nxd2 O-O.

After 3.e4?! Black gains a crushing attack via 3...Nxe4 4.dxe5 Bc5 5.Nh3 d6 6.Qe2 f5 7.exf6 O-O! 8.fxg7 Re8 9.Be3 Bxe3 10.fxe3 Bxh3 11.gxh3 Qh4+.

After 3.Bg5?! the game Ladmann – Tartakower (Scarborough 1929) continued with 3...exd4 4.Qxd4 Be7 5.Nf3 Nc6 6.Qd1 Ne4 7.Bxe7 Qxe7 8.a3 d6 9.e3 O-O 10.Be2 Qf6 11.Nbd2 Bf5 when both Tseitlin and Borik assess the position as favourable for Black.

After 3.Nf3?! the game Menchik – Tartakower (Paris 1929) continued with 3...e4 4.Nfd2 d5 5.cxd5?! Qxd5 6.e3 Bb4 7.Nc3 Bxc3 8.bxc3 O-O and White has problems to develop his kingside because of the potential weakness of g2. Another way is 3...exd4 4.Nxd4 d5 5.cxd5 Qxd5 6.Nc3 Bb4 7.Qa4+ Nc6 8.Nxc6 Bxc3+ 9.bxc3 Bd7 with a black advantage.