Petra Kvitova ended the run of a resurgent Venus Williams at the Pan Pacific Open on Friday, winning a high-octane shootout 3-6, 6-3, 7-6 to reach the final of the $2.3m event, where she will face fellow "lefty" Angelique Kerber.
The German Kerber had too much firepower for Denmark's Caroline Wozniacki, the fifth seed beating the former world number one 6-2, 7-6 to reach her seventh career final.
Kvitova, the 2011 Wimbledon champion from the Czech Republic, repelled everything Williams threw at her in a pulsating Tokyo semi-final, the seventh seed holding her nerve to tear through the deciding tiebreak 7-2 and complete victory in two hours, 24 minutes.
"That was definitely one of my best matches of the season," Kvitova told AFP after playing her third match in two days.
"I knew she would attack and I had a little trouble so I just tried to do the same to her."
A see-saw match which began in bright sunshine with Williams in the ascendancy caught fire in the second set.
Kvitova began ripping winners past the former world number one, who took the rare step of calling hitting partner David Witt to her chair for a pow-wow after being pegged back to a set-all.
But Kvitova refused to buckle, finding the sweet spot repeatedly - to the frustration of the seven-times grand slam singles champion, whose ranking has plummeted to 63rd in the world after being diagnosed with an autoimmune disorder in 2011.
The American unravelled at crunch time and an absorbing clash ended under floodlights when Kvitova, who had held a 6-0 lead in the tiebreak, converted her third match point by forcing Williams to hook a forehand long after another fierce salvo from the baseline.
"I guess I was a little tired," sighed Williams, who had taken over three hours to win her quarter-final against Canadian teenager Eugenie Bouchard.
"But she played an amazing tiebreak. There were a few painful misses," added the 33-year-old, projected to rise to 38 in the new rankings next week.
"That happens. At least I went for it."
Kvitova, who has been ranked as high as two, had been forced to play twice on Thursday after rain caused a backlog of matches.
"I felt a little tired when I woke up but I'm always like that in the morning," said the 23-year-old, looking to capture her second title of the year and 11th of her career in Saturday's final after winning in Dubai earlier this year.
"I knew how Venus would play and I had a strategy for her."
Williams won the last of her 44 singles titles at last October's Luxembourg Open and last won a grand slam with a fifth Wimbledon triumph in 2008.
"It will be very tough against Petra," said Kerber after ousting 2010 Tokyo winner Wozniacki.
"She is playing at a very high level so I have to match that," added the German, seeking a third career title and a first of 2013. "I'll try not to get too nervous and stick to my game plan."