Caroline Wozniacki has retired from her semifinal match at the New Haven Open with a knee injury, her first loss at the tournament.
Wozniacki, who injured the knee in her quarterfinal win on Thursday, lost the first set of the semifinal to Maria Kirilenko, 7-5, when she called for the trainer.
It was the first set she had lost in New Haven since 2010. The four-time defending champion had won 20-matchs in a row at the tournament.
Wozniacki says she decided to play after doctors told her she was not likely to make the injury worse. But she says it bothered her throughout the set.
She says she will rest the leg for a couple of days and hopes to be ready for the U.S. Open.