1998 ATP Tour World Championships – Singles

Àlex Corretja defeated Carlos Moyá in the final, 3–6, 3–6, 7–5, 6–3, 7–5 to win the singles tennis title at the 1998 ATP Tour World Championships. He would ultimately become the first player to win the title without ever winning a major in his career. The final was a rematch of that year's French Open final, where Moyá prevailed.

Pete Sampras was the two-time defending champion, but was defeated in the semifinals by Corretja.

Seeds
• # 🇺🇸 Pete Sampras (semifinals)

• # Marcelo Ríos (round robin, withdrew due to a back injury)

• # 🇺🇸 Andre Agassi (round robin, retired due to a back injury)

• # 🇪🇸 Carlos Moyá (final)

• # 🇪🇸 Àlex Corretja (champion)

• # 🇸🇰 Karol Kučera (round robin)

• # 🇬🇧 Tim Henman (semifinals)

• # 🇷🇺 Yevgeny Kafelnikov (round robin)

• # 🇬🇧 Greg Rusedski (round robin)

• # 🇪🇸 Albert Costa (round robin)

Red group
''Standings are determined by: 1. number of wins; 2. number of matches; 3. in two-players-ties, head-to-head records; 4. in three-players-ties, percentage of sets won, or of games won; 5. steering-committee decision.''

White group
''Standings are determined by: 1. number of wins; 2. number of matches; 3. in two-players-ties, head-to-head records; 4. in three-players-ties, percentage of sets won, or of games won; 5. steering-committee decision.''