World number two Caroline Wozniacki injured her right ankle and retired from her semi-final match against Vera Zvonareva at the WTA's Family Circle Cup here on Saturday. The second-seeded Dane was down 2-4 in the first set against Zvonareva, the seventh seed from Russia, when she slid on the green clay trying to get to the net for a drop shot. Her foot stuck briefly and her ankle rolled over, the 19-year-old immediately clutching it in pain. She was helped to her chair and had the ankle taped, returning to the court to cheers from the crowd. But after Zvonareva held to take a 5-2 lead, Wozniacki double-faulted at 15-15 and called it quits. Wozniacki had been seeking her second title in as many weeks, after a triumph at Ponte Verde Beach last Sunday. Zvonareva awaits the winner of the remaining semi-final between Slovakian Daniela Hantuchova and Australian Samantha Stosur. 