China's Zheng Qinwen saw off a spirited challenge from Diana Shnaider to secure a hard-fought win in their Pan Pacific Open semi-final in Tokyo and set up a title clash against American Sofia Kenin.

Zheng's 7-6 (7-5) 6-3 victory on Saturday sealed a spot in the final for the second time in her career, and she will be looking to make amends for her 2022 loss to Russia's Liudmila Samsonova.

The Olympic champion and top seed wasted little time in the semi-final, breaking twice in quick succession to race to a 4-0 lead and put Shnaider on the back foot, but a drop in Zheng's level gave the Russian an opportunity to claw her way back into the contest.

Shnaider won three straight games to leave the opening set at 4-3, before defending three set points to hold under pressure for 5-4, then saving another to break Zheng's serve for a second time and level at 5-5.

Zheng recovered to force a tiebreak, where the 22-year-old won three consecutive points to take the opening set.

Early in the second set, Zheng's first-serve percentage plummeted and Shnaider broke for 2-1, but the top seed broke right back and again for a 4-2 lead she would not relinquish.

"It was not an easy match, especially because I was way forward with a lot of set points, and then the end of the set, in the tiebreaker, it was not easy," Zheng said.

"I'm just happy I'm always there (in the match). It doesn't matter what happens today on court. I'm happy to be back in the final again because I was here two years ago."

Earlier, 2020 Australian Open champion Kenin eased past British No.1 Katie Boulter 6-4 6-4 in just under 90 minutes to reach her first singles final since San Diego last year.

Kenin, 25, also finished runner-up at the French Open in 2020 and reached a career-high No.4 that season, before injuries, illness and off-court issues saw her drop down the rankings.

"I think she's a really good player and she has a good groundstroke and she has some great drop shots," Zheng said of Kenin.

"Of course, if she's in the final, it means she's really tough to beat in this tournament. I'm just going to try my best tomorrow and let's see what happens."