ISTANBUL (AP) -- Maria Sharapova swept past Sam Stosur 6-0, 6-3 at the WTA Championships on Friday to retain a small chance of finishing the year as the No. 1-ranked player.

But if Victoria Azarenka beats Li Na in the final match of the day, Azarenka will be assured of staying at No. 1.

Sharapova has already qualified for the semifinals of the elite, eight-woman event.

The Russian rolled through the first set, allowing Stosur only five points. Stosur was an alternate who replaced defending champion Petra Kvitova, who withdrew because of illness.

Stosur put up more of a fight in the second set, but Sharapova ended it with a smash.

Sharapova won the French Open this year and briefly held the No. 1 ranking.

SI Apps
We've Got Apps Too
Get expert analysis, unrivaled access, and the award-winning storytelling only SI can provide - from Peter King, Tom Verducci, Lee Jenkins, Seth Davis, and more - delivered straight to you, along with up-to-the-minute news and live scores.