ISTANBUL (AP) Wimbledon champion Petra Kvitova defeated Vera Zvonareva of Russia 6-2, 6-4 Tuesday in the opening match at the WTA Championships.

Kvitova was making her first appearance at the season-ending tournament for the top eight players in Istanbul. It was tied 4-all in the second, after Kvitova wasted a 4-1 lead, before she broke her opponent again to wrap up the win.

The victory gave the Czech player an early lead in the Red Group, which includes top-ranked Caroline Wozniacki of Denmark and Agnieszka Radwanska of Poland.

Wozniacki is scheduled to play Radwanska, while Maria Sharapova faces U.S. Open champion Sam Stosur.