Defending champion Aryna Sabalenka will clash with Chinese 12th seed Zheng Qinwen in the Australian Open final after both women powered to straight-sets victories in the last four on Thursday.

World number two Sabalenka kept her title defence on track by blasting past American fourth seed Coco Gauff 7-6 (7/2), 6-4 with the roof closed on Rod Laver Arena.

Zheng then stormed into a debut championship match with a stirring 6-4, 6-4 victory over gallant Ukrainian qualifier Dayana Yastremska.

In doing so, the 21-year-old became the first Chinese finalist in Melbourne since her idol Li Na won the title in 2014.

Zheng's previous best Slam showing was the quarter-finals at the US Open last year, when she was easily beaten by Sabalenka in their only previous meeting.

The Belarusian will be favourite again to claim her second major crown on Saturday in what promises to be a bruising showdown between two hard-hitters who sometimes train together.

"I was able to focus on myself," said Sabalenka of beating Gauff and avenging her defeat in last year's US Open final.

"I was prepared that she was going to move well and put all the balls back and I was just ready for anything. That was the key, and the support here."

The win ensured she became the first player since Serena Williams in 2016 and 2017 to reach back-to-back Australian Open finals.

No one since Victoria Azarenka in 2013 has mounted a successful women's title defence at Melbourne Park.

Sabalenka said before her match that she was motivated by revenge after 19-year-old Gauff's breakthrough three-set triumph at Flushing Meadows.

But it proved to be her toughest assignment at the tournament so far, having dropped just 16 games leading into the clash.

"It's always a great fight (against Gauff). She's a great player and I enjoy playing her," she said. "I really hope that in the future we are going to play many more finals."

- Positive -

There were six service breaks in an unpredictable opening set that Sabalenka led 5-2 before the American came storming back to set up a tiebreak that the Belarusian dominated.

Gauff saved two break points in a crunch 11-minute game to open the second set before the match settled into a more normal rhythm, with eight straight service holds

That all changed in the ninth game when Sabalenka dialled up the pressure, attacking Gauff's second serve to break for 5-4 and serving out for the win.

"Tough match for me tonight, but overall a positive tournament," said Gauff.

"I had chances in both sets, but she played better."

Zheng, whose exploits ensure she will break into the world's top 10 for the first time next week, was buoyed by a large Chinese contingent in the crowd.

Yastremska broke first, but four double faults in the next game immediately nullified her advantage.

Zheng broke again in the seventh game, after which the Ukrainian left the court, apparently for treatment for a stomach issue.

She returned but failed to get back on terms.

The players exchanged service breaks in the second set before Zheng broke to love in the seventh game, which ultimately proved decisive.

"I'm super-excited to have such a great performance today and arrive in the final," said Zheng, who was lifted by meeting Li Na in Melbourne last week for the first time.

"My opponent was playing unbelievable tennis. It is tough to explain my feelings now."

Zheng won her first WTA title at Palermo and followed it up with a second in Zhengzhou at the back end of last year, while making the last eight at the US Open and winning an Asian Games gold medal in a breakthrough season.