See main article: 1990 ATP Tour World Championships.
Andre Agassi defeated the defending champion Stefan Edberg in the final, 5–7, 7–6(7–5), 7–5, 6–2 to win the singles title at the 1990 ATP Tour World Championships.
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.
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.