TOKYO -- Top-ranked Maria Sharapova retired during the second set of her Pan Pacific Open semifinal against Ana Ivanovic on Saturday because of a hamstring injury.
After dropping the first set 6-1, the Russian star consulted with her trainer. She won the first game of the second set before retiring.
"It's disappointing to have to finish this way," Sharapova said. "I started to feel pain in the second game of the first set. I tried to go on, but you can't get away with it when you are playing against a top player."
Fifth-seeded Ivanovic of Serbia will face second-seeded Martina Hingis in the final Sunday.
Hingis posted a 6-4, 6-3 win over defending champion Elena Dementieva of Russia.
Sharapova, who reclaimed the No. 1 spot in the WTA Tour rankings Monday, lost to Serena Williams in the final of the Australian Open.
The Russian had 17 double-faults in her first match against Italy's Francesca Schiavone and double-faulted 14 times Friday in the quarterfinals against Japan's Ai Sugiyama. Sharapova refused to blame the injury on her schedule.
"I have a simple and easy schedule compared to the other girls," she said. "There's no doubt its difficult when you come straight from a Grand Slam. The surface here is quite different and the change in court might have something to do with it."
Sharapova said her trainer told her she would likely need about a week to recover.
"I didn't have pain like this during the Australian Open," added Sharapova. "This is like a sudden, sharper pain I felt when I landed on the serve."
In Saturday's second semifinal, Hingis raced to a 3-0 lead in the first set.
"It was a great start for me in the beginning," Hingis said. "I had a bad experience last year when I lost to her in the final, so I was happy to get a little revenge today."
Hingis has won this tournament four times and will be looking to set a tournament record Sunday.
"I share the record for most wins here with Lindsay Davenport and hopefully can set the record tomorrow," Hingis said. "It will be a tough match. Ana has played well all week, but I'm looking forward to it."