Petra Kvitova rallied to defeat Venus Williams 3-6, 6-3, 7-6 (2) on Friday and advance to the Pan Pacific Open final.
The seventh-seeded Kvitova dominated the tiebreak, jumping out to a 6-0 lead. Williams won the next two points before the Czech player capitalized on her third match point.
Williams had been bidding for her first title since winning in Luxembourg last October.
"I was probably a little tired," said Williams, who endured a three-hour, three-setter on Thursday. "But I don't think it affected the match. She played two matches yesterday so no doubt was a little tired as well."
Kvitova, who held off 11 break points, will face either fourth-seeded Caroline Wozniacki or No. 5 Angelique Kerber.
"I am really happy with how I played today," Kvitova said. "It was a very close match and every game was up and down."