SYDNEY (AP)—Former Wimbledon champion Petra Kvitova advanced to the Sydney International semifinals on Wednesday with a 7-6 (4), 6-2 victory over fellow Czech player Lucie Safarova.

Kvitova, the second seed, will play Tsvetana Pironkova for a spot in the final. Pironkova defeated third-seeded Sara Errani, 7-6 (2), 6-3.

In other women's play, defending champion Elena Vesnina retired from her second-round match at the Hobart International with a back injury. Spanish qualifier Estrella Cabeza Candela was leading the match 4-6, 6-2, 4-1 when Vesnina quit.

At the ATP tournament in Auckland, New Zealand, American wild card Jack Sock defeated second-seeded German Tommy Haas 6-4, 6-4. American John Isner, the third seed, also advanced with a 7-6 (1), 3-6, 6-2 win over Slovakian Lukas Lacko.