ISTANBUL (AP) Maria Sharapova lost her second straight match at the WTA Championships, a 7-6 (4), 6-4 defeat to Li Na on Wednesday.
That leaves Sharapova on the brink of elimination from the season-ending tournament, but she still has a slim chance of advancing to the semifinals if she wins her final round-robin match against Victoria Azarenka.
Azarenka maintained her perfect record against Sam Stosur with a 6-2, 6-2 win.
Sharapova led 4-2 in the first set before Li broke back to force the tiebreaker, where the Russian let a 4-0 lead slip away. Li took a 5-2 lead in the second set and served out the match on her second attempt.
Li, the French Open champion, is the first Chinese player to qualify for the season-ending event for the world's top eight players.
Stosur, the U.S. Open champion, was coming off her first win over Sharapova on Tuesday evening but appeared flat for Wednesday's opening match.
The fourth-ranked Azarenka broke four times to improve to 5-0 against Stosur.
I didn't play aggressive enough ... I don't feel like I did anything,'' Stosur said.I just kind of got pushed around the court, and eventually was made to make an error or she would hit a winner.''
The Australian said her performance wasn't affected by the late match against Sharapova.
Oh, I can't blame that,'' she said.Yeah, it was a quick turnaround, but I felt like I was ready to go.''
In the Red Group, top-ranked Caroline Wozniacki will face Vera Zvonareva in the late match.