The world number one saw off Bai 6-3, 6-1, having threatened at one stage to complete the job in even more express fashion.

She faces Russia-born Austrian Anastasia Potapova next as the Belarusian chases a third Melbourne crown in four years.

Sabalenka was stunned in the final 12 months ago by Madison Keys but otherwise has been almost unbeatable on the Melbourne Park hard courts since 2023.

"That sounds crazy and surreal, to be honest," she said, when it was put to her that her Australian Open record in recent years was up there with the likes of Serena Williams and Steffi Graf.

"Just never thought that people will kind of like compare me to these names, even though I'm really far away from their achievements.

"Of course it sounds incredible... it motivates me to keep doing my thing.

"It just means for me that I'm on the right track."

Sabalenka won the first nine points in a row to surge into a 2-0 lead at Rod Laver Arena against her outclassed opponent ranked 702 in the world.

After just eight minutes it was 3-0, then 5-0, with Sabalenka seemingly intent on getting the job done in time for an early lunch.

But the 23-year-old Bai, playing the biggest match of her life, worked through her nerves and finally held serve.

She then stunned centre court by breaking Sabalenka's serve to reduce the deficit to 5-2, and doggedly held her own serve for 5-3.

The 27-year-old US Open champion Sabalenka was beginning to show signs of frustration as she saw numerous set points come and go.

She finally got the job done after 39 minutes on her seventh chance, slamming a ball she was holding in her hand down on the court in a flash of anger.

The second set was more serene, Sabalenka's superior power taking its toll as she sealed the match in 72 minutes.

"Tricky opponent," said Sabalenka.

"Super-happy to close the (first) set, it gives me confidence that my game is there, my focus is there.

"Step by step. There is always a little gap to improve."