Wozniacki in semifinals

World No.2 Caroline Wozniacki, who will be the top seed at the U.S. Open next week, got some much-needed rest on Thursday when her quarterfinal opponent Flavia Pennetta withdrew with a foot injury in the Pilot Pen Open.

Italian Pennetta was reluctant to pull out of the tournament but said she wanted to give herself every chance of playing at the U.S. Open.

In the men's quarterfinals, Ukraine's Sergiy Stakhovsky toppled top seed Marcos Baghdatis of Cyprus 5-7, 6-1, 7-6(4).

The results (quarterfinals):

Men: Thiemo de Bakker bt Evgeny Korolev 6-4, 6-3; Sergiy Stakhovsky bt Marcos Baghdatis 5-7, 6-1, 7-6(4); Denis Istomin bt Teimuraz Gabashvili 6-1, 3-6, 7-6(8); Viktor Troicki bt Radek Stepanek 6-2, 6-3.

Women: Maria Kirilenko bt Dinara Safina 6-3, 6-3; Nadia Petrova bt Samantha Stosur 6-2, 6-1; Caroline Wozniacki bt Flavia Pennetta, walkover; Elena Dementieva bt Marion Bartoli.