Naomi Osaka will face world number one Ashleigh Barty in the China Open final after surging past defending champion Caroline Wozniacki.

Australia Open winner Osaka hit 30 winners in beating Wozniacki 6-4 6-2 in one hour 24 minutes in Beijing.

Barty, who won the French Open, earlier battled past Kiki Bertens 6-3 3-6 7-6 (9-7) in their semi-final on Saturday.

Sunday's final will be the fourth meeting between Japan's Osaka and Barty, with the Australian leading 2-1.

Osaka, 21, started strongly but Wozniacki held on until the ninth game, when Osaka broke and served out to claim the set.

The world number four, who hit five aces and saved all seven break points against her, broke the 29-year-old Dane twice in the second set as she raced to victory.

Osaka said she barely slept before the semi-final after ending US Open champion Bianca Andreescu's 17-match winning streak in the quarter-finals late on Friday.

"I went to sleep at 4:00 am, I woke up at 6:00 am, so solid two hours, I can't really sleep after my matches," she said.

"I just feel like my adrenaline's up more during the tougher matches so it makes it harder to sleep."

Barty, 23, had to save match point in a thrilling tie-break decider against the Netherlands' Bertens, also committing 52 unforced errors in a nervy showing.

The top seed dominated the first set only for Bertens, 27, win the second by the same score.

Bertens broke in the fifth game of the decider but could not serve out for the match as Barty hit back to take it to a tie-break.

The Australian trailed 3-0 in the tie-break but rallied to set up match point at 6-5, before Bertens won the next two to get a match point of her own.

But Barty drew level and reeled off the next two points to wrap up victory in two hours 20 minutes.

Barty credited a "massive growth" in her mental strength in playing decisive points.

"It's gone hand-in-hand with adding some new people to my team, trying to work with them behind the scenes," she said.

"Not just for my tennis - it's for my life, my health and wellbeing, as well, which has been the best thing.

"I have never been happier off the court, never been happier on the court."