Amelie Mauresmo won't enjoy her 34th consecutive - and last - week as women's No. 1 unless she beats Justine Henin-Hardenne on Friday to reach the WTA Championships semifinals.
Top-ranked Mauresmo rallied for a 3-6, 6-1, 6-4 win over No. 8 Martina Hingis on Thursday to set up her match with third-ranked Henin-Hardenne knowing it's win at all costs if she hopes to defend her title.
"For me, I need to go out and win that match. It's the only solution for me to qualify," Mauresmo said. "That's why also tomorrow I'm really looking forward, you know, to do even better than I did tonight."
Mauresmo holds a 2-1 advantage over Henin-Hardenne this year, and has beaten the Belgian when it counts most - in Grand Slam finals at Wimbledon and the Australian Open.
Henin-Hardenne remained the favorite to finish as year-end No. 1 after her 6-4, 6-4 win over Nadia Petrova guaranteed passage to the semis.
"I'm not going to change my goal right now - it's to try to win every match," Henin-Hardenne said. "There's one more match tomorrow in my group then I can be focused on the semifinal, but I will play with the goal to go into the final and not to be No. 1."
No. 2-ranked Maria Sharapova can secure her place in the semis with a win over Svetlana Kuznetsova on Friday, but she could also lose and advance as long as she takes a set from the world No. 4.
Two-time winner Kim Clijsters beat Kuznetsova 6-1, 6-1, and could reach the semis for the first time since her second championships title in 2003.
Clijsters will advance from the Red Group if she beats winless Elena Dementieva on Friday.
Petrova's defeat to Henin-Hardenne meant the Russian cannot advance from the Yellow Group on a countback of sets whatever the result between Mauresmo and Henin-Hardenne.
Former No. 1 Hingis, championships winner in 1998 and 2000, will advance to the semis if Mauresmo loses.
"I usually don't like relying upon other people, I just normally like to get there myself," Hingis said. "But, hey, it's still a chance to get there. And with me winning at least a set today, it definitely gives myself a better chance to make it."