DOHA, Qatar(AP) Caroline Wozniacki overcame severe leg cramps and a challenge from Vera Zvonareva to win 6-0, 6-7 (3), 6-4 Thursday at the Sony Ericsson Championships.

Wozniacki needed two medical time-outs to treat her cramping left thigh in the third set and collapsed to the court sobbing and clutching both legs after netting a forehand at 30-15 in the last game. But she got back up and clinched the win when Zvonareva netted a forehand.

The 19-year-old Dane then broke into tears again and limped toward her chair. It was her second win in the round-robin phase of the tournament, putting her on the verge of the semifinals.

Zvonareva replaced Dinara Safina as an alternate, after the Russian pulled out with a back injury.