Wozniacki, Sharapova headline WTA Championships

ISTANBUL - Top-ranked Caroline Wozniacki and three-time major winner Maria Sharapova lead two round-robin groups for the WTA Championships this week as Turkey's biggest city hosts the event for the first time. Wozniacki is joined in the red group by Wimbledon champion Petra Kvitova, Vera Zvonareva and Agnieszka Radwanska. Sharapova, Victoria Azarenka, French Open champion Li Na and U.S. Open winner Samantha Stosur are in the white group. Each player meets the other three players in their group, and the top two in each pool move into the semifinals. The final is on Sunday.