TOKYO -- Rising teenager Zheng Qinwen continued her winning run at the Toray Pan Pacific tournament Saturday, beating the sole remaining seed Veronika Kudermetova 5-7, 6-3, 7-6 (3) in the semifinals at the Ariake Coliseum.
In a match that lasted a little over three hours, Zheng and fourth-seeded Kudermetova traded huge ground shots, big serves and plenty of errors as they pushed each other to the limits.
Zheng, who ousted top seed Paula Badosa in the second round, had an early advantage after breaking Kudermetova in the fourth game, but the Russian player stayed on track and broke the 19-year-old Chinese player in the seventh and ninth games to secure the set.
There was just one break of serve in the remainder of the match, when an error by Kudermetova gave Zheng the advantage in the second set.
Zheng had to save herself on many occasions, but her errors were often matched by great recoveries. The grueling match started to take its toll on Kudermetova, and she needed a medical timeout for an arm problem after going 6-5 up in the final set.
World No. 36 Zheng then served to love to set up the tiebreak, and errors by Kudermetova, including a double-fault at 2-5, saw the Russian's hopes of reaching the final unfold.
Zheng, who will be in her first final, will need to be much more efficient to beat Samsonova, especially on her own service games. She had eight aces to Kudermetova's six but 24 more second serves than her opponent.
"I feel so amazing to arrive in the final," Zheng said. "Today was a really, really difficult match. Every point was so important, and there were a lot of emotions. My opponent played really good. She has a good serve and really good baseline shots, and it was not easy."
Samsonova, who has won two tournaments this year and reached the fourth round of the US Open in August, sent down an early message in her first service game against Zhang with a couple of aces that topped 110 mph.
She broke the 33-year-old Chinese player in the next game with some powerful ground strokes. But she was also broken in her second service game after some unforced errors, recovering to win her next two service games to love.
World No. 28 Zhang played steady tennis, but the 30th-ranked Samsonova's errors kept the match even as the set headed to a tiebreak. A blistering forehand into the right corner gave her set point, which she closed out with one of her 13 aces.
After breaking Samsonova in the first game of the second set, Zhang then blew a 40-0 lead in the next game and lost her own serve.
Zhang didn't appear to have any answers as the 23-year-old Russian player upped her game. Zhang was broken in her final two service games, effectively ending the contest.
"I didn't expect this at all," said Samsonova, who beat Wimbledon champion Elena Rybakina in the first round and third-seeded Garbine Muguruza in the quarterfinals. "I came here to try to play my best, and I'm in the final.
"It's amazing. It was a very mental game because she was playing amazing, so I tried to stay in there and play with her game. It was tough, but in the tiebreak I think I played better."