Seles won her first Grand Slam singles title at the French Open in 1990. Facing World No. 1 Graf in the final, she saved four set-points in a first-set tie-breaker, which she won 8-6, and went on to take the match in straight-sets. In doing so, she became the youngest-ever French Open champion at the age of 16 years, 6 months. She also won the 1990 season-ending championships, defeating
Gabriela Sabatini in five sets, finishing the season ranked No. 2.
1991 was the first of two years in which Seles dominated the women's tour. She started out by winning the
Australian Open in January, beating
Jana Novotná in the final. In March, she replaced Graf as the World No. 1. She then successfully defended her French Open title, beating the former youngest-ever winner
Arantxa Sánchez Vicario in the final. However, instead of playing at
Wimbledon, she took a six-week break, blaming
shin splints. But she was back in time for the
U.S. Open, and won it beating
Martina Navrátilová in the final to cement her position at the top of the world rankings. She also won the season-ending championships, beating Navratilova in four sets.
1992 was an equally dominant year. She successfully defended her titles at the Australian Open, the French Open, and the U.S. Open. She also reached the final at Wimbledon, but could not manage to break Graf's dominance on the
grass court surface and lost 6-2, 6-1. Some observers, however, attribute her lop-sided loss to her decision to remain silent throughout the match, resulting in less penetrating shots. Two opponents (including Navrátilová in the semifinals) had strongly complained about Seles' screams.
During the period from January 1991 to February 1993, Seles won 22 titles and reached 33 finals out of the 34 tournaments she played. She compiled a 159-12 win-loss record (92.9% winning percentage), including a 55-1 win-loss record in Grand Slam tournaments. In the broader context of her first four years on the circuit (1989-1992), Seles had a win-loss record of 231-25 (90.2% winning percentage) and collected 30 titles. Only Evert had a better first four years in terms of winning percentage (91.1% from
1971 to
1974) and titles (34) in the open era..