Maria Sharapova Tennis: Maria Sharapova in Tokyo

TOKYO -- Second-seeded Maria Sharapova was eliminated from the Pan Pacific Open on Thursday when she was forced to retire because of an injury in the first set of her quarterfinal match against Petra Kvitova.

With her Czech opponent leading 4-3 in the first set, Sharapova twisted her left ankle when serving in the eighth game. She limped to her chair and pulled out after speaking with her trainer.

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"I hit a serve and then landed awkwardly on my left ankle," said Sharapova, who went to a hospital for an MRI. "I felt a sharp pain and next thing I knew I was on the floor. It swelled up immediately and I knew there was no way I could continue."

Thursday's quarterfinal was a rematch of this year's Wimbledon final, where Kvitova beat Sharapova 6-3, 6-4 for her first major title.

"It's sad because we were both playing so well," Kvitova said. "It was a great match but I could see (the ankle) was really big. Hopefully, she will be OK."

In Friday's semifinals, Kvitova will face fourth-ranked Vera Zvonareva of Russia, who defeated Maria Kirilenko 6-3, 6-3.

"I played her already three times, the last time in Madrid on clay when I beat her," Kvitova said. "She's a very good player. She has a great serve and hits the ball well so it will be a tough match."

Zvonareva had five aces and improved to 6-0 in head-to-heads against the unseeded Kirilenko.

"I'm really happy that my serve helped me today," Zvonareva said. "The first serve was good and my second serve even caused her some problems, and that made a big difference."

Kirilenko knocked out U.S. Open champion Samantha Stosur on Tuesday and beat 12th-seeded Ana Ivanovic on Wednesday, but struggled with her serve against Zvonareva and was broken three times.

"Maria is a great player and a great fighter, and proved it by beating two tough opponents on her way to the quarterfinals," Zvonareva said. "There is no secret to beating her. I just tried to make some shots that caused her some discomfort and was able to do that."

Also, third-seeded Victoria Azarenka of Belarus beat seventh-seeded Marion Bartoli of France 7-5, 6-0 to reach the final four. She next will face Agnieszka Radwanska of Poland, who beat Kaia Kanepi of Estonia 6-2, 7-6 (7).

Maria Sharapova