Sharapova moves to 3-0 at WTA Championships

French Open champion Maria Sharapova went 3-0 in her round-robin matches this week at the season-ending WTA Championships.

The second-seeded former world No. 1 star breezed past ninth-seeded replacement Samantha Stosur 6-0, 6-3 indoors at Sinan Erdem Dome. The sturdy Aussie Stosur went 0-2 in her round-robin affairs after replacing ill 2011 Championships titlist Petra Kvitova in the elite eight-player field on Wednesday.

The 2004 champion and 2007 WTA Championships runner-up Sharapova reached the semifinals and captured this week's four-player White Group, which also features Wimbledon runner-up Agnieszka Radwanska (1-1) and French Open runner-up Sara Errani (1-1). The fourth-seeded Radwanska and seventh-seeded Errani are currently battling for a spot in the semis.

Also on Day 4 in Istanbul, current world No. 1 Victoria Azarenka (1-1) will take on eighth-seeded Li Na (1-1) in the last of the Red Group action. The winner will join Sharapova and third-seeded former No. 1 Serena Williams (3-0) in the semifinals.

If Azarenka wins on Friday she would end the year at No. 1 for the first time in her career and become the 11th woman to do so. If she should lose, Sharapova would finish the year at No. 1 with a perfect record, including a title, this week.

The Australian Open champion Azarenka was last year's WTA Championships runner-up to Kvitova.

In addition to Azarenka, Williams and Li, the Red Group also featured fifth- seeded German Angelique Kerber, who went 0-3 in her round-robin play.

Saturday's semifinal winners will meet in the lucrative final on Sunday. If Sharapova or Williams title this week, one of them would claim $1.75 million as an undefeated champion.

The sizzling-hot Williams has won 46 of her last 48 matches overall and is a perfect 12-0 against top-five players this season.

The 31-year-old star is the reigning Wimbledon, U.S. Open and Olympic champion and captured WTA Championships titles in 2001 and 2009 and is a two-time runner-up at this prestigious event.