Japan's Naomi Osaka crushed Italian Camila Giorgi 6-2, 6-3 in Tokyo on Saturday to set up a Pan Pacific Open final against Czech Karolina Pliskova.
Third seed Osaka needed just 71 minutes to complete her 10th straight win after capturing a historic US Open title earlier this month.
Former world number one Pliskova beat Croatia's Donna Vekic 6-2, 4-6, 6-3 but took well over two hours to get the job done.
Osaka, however, made quick work of a dangerous opponent who had knocked out top seed and defending champion Caroline Wozniacki, breaking twice in a one-sided first set which she took with a blistering forehand down the line.
The 20-year-old, who has climbed to seventh in the world rankings since her stunning victory over Serena Williams in New York, piled on the pressure in the second.
A brutal Osaka forehand forced a break in the fifth game, before a vicious backhand return forced Giorgi to whiff a shot beyond the baseline on match point.
"I was pretty nervous because I really wanted to get to the final," said 2016 runner-up Osaka, who fired down nine aces in a dominant display.
"She was playing really well and I felt like I was just trying to survive. But I served really well and that got me out of a lot of trouble today."
Fourth seed Pliskova took just 12 minutes to secure a 4-0 lead before closing out the first set with one of her 11 aces.
Vekic hit back to take the second as Pliskova's serve imploded -- the world number eight blotting her copybook with seven double-faults, many of them coming on key points.
But Pliskova snaffled an early break in the decider and hung on to reach her first Tokyo final, a forehand rocket ending her opponent's spirited resistance.
Wawrinka in semis
Stan Wawrinka beat last year's St Petersburg champion Damir Dzumhur in straight sets to reach the semifinals on Friday in Saint Petersburg.
The 33-year-old Swiss wild card beat the Bosnian, who was seeded sixth, 6-3, 6-4 in one hour and 11 minutes to level their head-to-head record at one all.
"The level of my play was good today and the win makes me feel positive," Wawrinka said.
In the last four, Wawrinka will face Slovak Martin Klizan, the 2012 champion, who battled back from a set down to beat seventh-seeded Denis Shapovalov of Canada 3-6, 7-5, 6-3.
French Open runner-up Dominic Thiem, the top seed in St Petersburg, also booked a place in the event's semis beating the local crowd's favourite Daniil Medvedev, seeded eighth here, 6-2, 3-6, 7-6 (7/2) in a hard-fought first meeting between the two.
Thiem will take on fifth-seeded Spaniard Roberto Bautista Agut, who saw off Italian third seed Marco Cecchinato 7-6 (7/0), 6-3, also in the pair's first ever meeting.
