Second-seeded Petra Kvitova will face Maria Kirilenko in the New Haven Open final after four-time defending champion Caroline Wozniacki pulled out with a knee injury on Friday, ending her remarkable sequence of victories.
Czech Kvitova breezed past Italy's Sara Errani 6-1, 6-3 while Kirilenko advanced when Wozniacki retired after losing the first set 7-5.
Kvitova, the 2011 Wimbledon champion, needed just 24 minutes to win the first set. She then broke Errani in the first game of the second set and cruised from there, closing out the match with another service break.
Wozniacki had won 20 straight matches at New Haven, but could not match Martina Navratilova, Steffi Graf and Chris Evert as the only women to win a tour tournament five straight times.
"I could feel it from the start," she said. "It just started to get a bit worse. I decided to stop because if you don't feel a hundred percent, you can't compete at a hundred percent. It's better to let it rest. I wasn't going to win this match anyway if I'm not on a hundred percent fit level."
The third-seeded Dane had swept all before her at New Haven since entering as a relatively unknown 18-year-old in 2008. She hadn't dropped a set here since the 2010 final.
"You defend it again and again, all of a sudden you're in this elite group that has won a tournament four times," she said. "There's a lot of players that never win a tournament and there's a lot of players that never win four. Winning the same one four times in a row is definitely special."
That was part of the reason she decided to play Friday, despite the injury, which she suffered in the quarterfinal on Thursday against Dominika Cibulkova. She went on to win that match 6-2, 6-1 after getting the knee taped.
She said medical experts had told her she would not hurt the knee further by playing Friday.
She seemed to move well during the match, but had a hard time with Kirilenko's serve and did not get single break point in the set.
Kirilenko broke Wozniacki in the 11th game and served out the set to avoid a tiebreaker.
"She was fighting," Kirilenko said. "She was running. When I hit a great shot, she couldn't run for it. She made the right decision. She has to take a rest before the U.S. Open."
The 25-year-old Russian will be playing her first tour final in the United States.
"Every match I feel that I'm improving," Kirilenko said. "I found the way to play again on hard court, as grass court is different completely than hard. Today I played the best tennis in this tournament."