World number one Maria Sharapova was forced to retire from her semi-final at the Pan Pacific Open in Tokyo with a hamstring injury.
Sharapova, who trailed Serbia's Ana Ivanovic 1-6 1-0 at the time, said she felt a sharp pain after serving in the second game of the first set.
"It's always difficult to end the tournament this way," said the 19-year-old Russian.
Ivanovic will now play second seed Martina Hingis in Saturday's final.
Hingis stayed on course for a fifth Tokyo title after she beat Elena Dementieva 6-4 6-3 to avenge a defeat by the Russian in last year's decider.
"It was a great start for me today and I didn't really miss a shot," said Hingis, who never looked back after racing into a 3-0 lead in the first set.
In the other match, fifth-seeded Ivanovic stormed into a one-set lead as an out-of-sorts Sharapova struggled with her serve and called for her trainer at the end of the first set.
Although the Russian won her first service game of the second set, she was clearly limping and retired from the game.
She revealed afterwards that she had been carrying a hamstring strain since the Australian Open.
"My left hamstring has been having tightness since the Australian Open but after a Grand Slam you are tight all over," said Sharapova, who lost to Serena Williams in last weekend's final in Melbourne.
"But this was a sudden sharper pain after I landed after the serve. I asked the trainer and she said these kind of strains take seven or 10 days to recover from, so hopefully I can recover quickly.
"I was hoping the pain would settle or get better, but against a top player it is hard to get away with not serving or returning well."