Caroline Wozniacki defeated Roberta Vinci of Italy 6-3, 6-1 Wednesday to advance to the semifinals of the Tournament of Champions.

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.

"I played solid and served very well. I am pleased with my performance,'' Wozniacki said.

Russian duo Nadia Petrova and Maria Kirilenko earned straight-set victories in their first group matches.

The second-seeded Petrova defeated No. 6 Zheng Jie 6-3, 6-3, handing her Chinese opponent a second loss in two days which will likely 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.

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