1999 Serena Williams tennis season

The Serena Williams 1999 season was her breakthrough season, winning her first career title at the Open Gaz de France and winning her first slam at the US Open.

Early hard court season
At the Australian Open, Williams lost in the third round to Sandrine Testud despite holding two match points. After two losses in tight three-setters in Australia, at the hands of Testud in Melbourne and Steffi Graf in Sydney, Williams won her first professional singles title when she defeated Amélie Mauresmo in the final of the Open Gaz de France in Paris, thus becoming the 13th unseeded player to win a Tier II or higher event since 1980. With Venus also winning the IGA Superthrift Classic in Memphis, Tennessee, that day, the pair became the first sisters to win professional tournaments in the same week.

In March of that year, at the Evert Cup in California, Williams won her first WTA 1000 event, defeating a 29-year-old Steffi Graf in the final, thus ending Graf's completed finals winning streak at 20, which dated back to 1995. Soon afterward at the Miami Masters, Williams had her 16-match winning streak ended by her sister in the first all-sister singles final in WTA history and the first all-sister women's final in 115 years, with the only other such final taking place at Wimbledon in 1884, when Maud Watson beat her older sister, Lilian, to become Wimbledon's first female champion. This was the best winning streak that includes a player's first title since Steffi Graf's 23-match streak in 1986. Williams then made her top-10 debut, at No. 9.

Clay court season
Williams lost in the quarterfinals of the Italian Open and the German Open. At the French Open, Williams lost in the third round to Mary Joe Fernández, but in the doubles event, she and Venus did not drop a single set en route to the final, where they defeated the pair of Martina Hingis and Anna Kournikova, who were the self-proclaimed "Spice Girls" of tennis, having dropped just a single set on their route to the Australian Open doubles title. It was the first major title for the Williams sisters and would be their first step towards completing the career Golden Slam in doubles.

Williams then missed Wimbledon because of injury. When she returned to the tour two months later, Williams made her Fed Cup debut. After a two-and-a-half-hour rain delay and with Monica Seles unavailable, the USTA and U.S. captain Billie Jean King turned to her other rookie, 17-year-old Serena, to try to close out the tie. Williams did just that, toppling Rita Grande, 6-1, 6-1, in 50 minutes, thus sending the U.S. back to the final for the first time since 1996. In doing so at 17 years and nine months old, she became the sixth youngest player in US Fed Cup history to win a match. The Williams sisters, who were traveling internationally without their parents for the first time in their careers, then teamed up to win the dead doubles rubber against Tathiana Garbin and Adriana Serra Zanetti, to cap a perfect debut. She then won her third title at the JPMorgan Chase Open in Los Angeles, beating Julie Halard-Decugis in the final. This moved her ranking back into the Top 10 at No. 9, tying her career high.

Late hard court season
At the US Open, Williams defeated Grand Slam champions Kim Clijsters, Conchita Martínez, Monica Seles, and defending champion Lindsay Davenport in consecutive matches to reach the final, where she faced the world No. 1, the 18-year-old Martina Hingis, who had defeated her sister in the semifinals and also in the 1997 US Open final. She finished the job that her sister could not by beating Hingis 6–3, 7–6(7–4) to capture her first US Open title at age 17 in only her second year as a pro; she won despite making 57 unforced errors, 33 more than Hingis. In doing so, she became the lowest seed to win the US Open in the Open era, the sixth American woman in the Open Era to win a Major, and only the second African-American woman, after Althea Gibson in 1958, to win a Grand Slam singles tournament.

In the doubles event, the Williams sisters defeated Chanda Rubin and Sandrine Testud in the final, 4–6, 6–1, 6–4 to win the women's doubles title. It was the second doubles major title for the Williams sisters, and their second step towards completing the career Golden Slam in doubles. Serena thus became the fifth woman in the Open Era to win both the singles and doubles event of a major, while she and Venus became the first sisters to win a US Open doubles championship in 101 years, since Juliette and Kathleen Atkinson accomplished it in 1897 and 1898. In total, the Williams girls earned $1.29 million for their two-week US Open travel, $915,000 of it reeled in by Serena.

To complete her 1999 season, Williams teamed up with Venus to win a doubles match in the Fed Cup final to help Team USA win the 1999 Fed Cup title against Russia at the Taube Family Tennis Stadium in Stanford, Calif. Williams ended the year ranked in a career-high world No. 4 in just her second full year on the main tour.

Singles schedule
Williams' 1999 singles tournament schedule is as follows:

Doubles schedule
Williams' 1999 doubles tournament schedule is as follows:

Mixed doubles schedule
Williams' 1999 doubles tournament schedule is as follows:

Head-to-head matchups

 * 🇺🇸 Lindsay Davenport 3–0
 * 🇫🇷 Julie Halard-Decugis 2–0
 * 🇪🇸 Magüi Serna 2–0
 * 🇺🇸 Monica Seles 2–0
 * 🇦🇷 Inés Gorrochategui 1-0
 * 🇷🇴 Raluca Sandu 1–0
 * 🇸🇪 Åsa Svensson 1–0
 * 🇫🇷 Nathalie Tauziat 1–0
 * 🇺🇸 Lisa Raymond 1-0
 * 🇺🇸 Kimberly Po 1–0
 * Jelena Kostanić 1–0
 * 🇫🇷 Laurence Courtois 1–0
 * 🇫🇷 Nathalie Dechy 1–0
 * 🇫🇷 Amélie Mauresmo 1–0
 * 🇨🇿 Jessica Steck 1–0
 * Cara Black 1–0
 * 🇫🇷 Mary Pierce 1–0
 * 🇦🇺 Alicia Molik 1–0
 * Amanda Coetzer 1–0
 * 🇺🇸 Jennifer Capriati 1–0
 * 🇧🇪 Kim Clijsters 1–0
 * 🇪🇸 Conchita Martínez 1–0
 * 🇮🇹 Rita Grande 1–0
 * 🇦🇷 Mariana Díaz Oliva 1–0
 * 🇷🇺 Tatiana Panova 1–0
 * 🇷🇴 Irina Spîrlea 1–0
 * 🇷🇺 Elena Likhovtseva 1–0
 * Patty Schnyder 1–0
 * 🇺🇸 Venus Williams 1–1
 * 🇩🇪 Steffi Graf 1-1
 * Martina Hingis 3–1
 * 🇪🇸 Arantxa Sánchez Vicario 2–1
 * 🇫🇷 Sandrine Testud 1–2
 * 🇺🇸 Mary Joe Fernández 0–1

Earnings
Figures in United States dollars (USD) unless noted.