Taipei: An ankle injury forced Maria Sharapova to retire from her quarter-final at the Pan Pacific Open in Tokyo, allowing Wimbledon champion Petra Kvitova to progress to the last four.
Sharapova, trailing 3-4, twisted her left ankle in the eighth game against the Czech fifth seed, who beat her in the Wimbledon final in July.
"I landed awkwardly on my left ankle. I felt a sharp pain and the next thing I knew I was on the floor," the Russian said.
"It swelled up immediately and I knew there was no way I could continue."
Kvitova faces Vera Zvonareva in the semi-finals after the Russian beat compatriot Maria Kirilenko 6-3, 6-3 in their quarter-final.
Third seed Victoria Azarenka beat Marion Bartoli 7-5, 6-0 to set up a semi-final clash against Poland`s Agnieszka Radwanska who beat Estonia`s Kaia Kanepi 6-2, 7-6.