Caroline Wozniacki advances
It was the second win for the top-seeded Dane in the group-stage format after her victory over Hsieh Su-Wei of Taiwan the previous day.
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"I played solid and served very well. I am pleased with my performance," Wozniacki said.
The second-seeded Petrova defeated No. 6 Jie Zheng 6-3, 6-3, handing her Chinese opponent a second loss in two days which likely will leave her without a chance of reaching the semifinals.
In the other match in the group, the third-seeded Kirilenko beat Tsvetana Pironkova 6-1, 6-4. Pironkova broke for a 2-0 lead in the second set but Kirilenko then won the next four games to take firm control of the match.
Petrova and Kirilenko will meet on Thursday.
Copyright 2012 by The Associated Press