Petra Kvitova of the Czech Republic defeated Yanina Wickmayer of Belgium 5-7, 6-3, 7-6 (3) on Friday to reach the semifinals of the Open Gaz de France.
Kvitova will face either Bethanie Mattek-Sands of the United States or Andrea Petkovic of Germany.
Kim Clijsters of Belgium can clinch the No. 1 ranking if she defeats Jelena Dokic of Australia in a later match on Friday.
Kvitova double-faulted to lose the first set to Wickmayer. But the fourth-seeded lefty broke for a 4-3 lead in the second set when Wickmayer netted a backhand. Kvitova evened the match on a double fault from the seventh-seeded Belgian.
Kvitova took a 4-1 lead in the tiebreaker and converted her second match point when an approach shot from Wickmayer sailed long.