Dementieva, seeded seventh, piled up seven service breaks in her 7-5, 6-2 win over Zvonareva. Zvonareva entered Thursday's match having won 12 of her last 14 matches, a string that included a finals appearance at the U.S. Open. But against Dementieva she had nine double faults and lost more points on serve than she won (43-34).
Dementieva moves into the tournament semifinals against No. 5-seeded Francesca Schiavone, who edged past Kaia Kanepi 7-5, 4-6, 7-5 in a quarterfinal match that took more than three hours. There were a total of 15 breaks of serve, including four in the final set by Schiavone.
The other semifinal will send top-seeded Caroline Wozniacki against No. 8-seeded Victoria Azarenka.
Wozniacki advanced when sixth-seeded Agnieszka Radwanska suffered a foot injury and was forced to retire. Wozniacki was ahead 5-0 in the first set at the time.
Azarenka ran past qualifier Coco Vandeweghe 6-2, 6-1 in 67 minutes. Azarenka won 68 percent of the points in the match.
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