The Belarusian world number one laid down the law to the 19-year-old in the first set before meeting resistance in the second on her way to a 6-1, 7-6 (7/1) win on Rod Laver Arena.

She will play another fast-rising teenager, American Iva Jovic, or Kazakhstan's Yulia Putintseva for a place in the semi-finals.

Sabalenka, a two-time Australian Open champion, is bidding to reach her fourth straight Melbourne final and avenge a shock defeat last year to Madison Keys.

While beating Mboko, she will not be happy with 24 unforced errors and letting slip a 4-1 lead in the second set.

"What an incredible player for such a young age, it's incredible to see these kids coming up on tour," she said.

"She pushed me really hard today and super happy with the win, and once again, in straight sets."

The hard-hitting Mboko arrived in Melbourne on the back of a breakthrough six months, winning her maiden WTA title in Canada in August, beating Coco Gauff and Naomi Osaka along the way.

She followed it up with victory at the Hong Kong Open and made the final of the Adelaide International this month before powering through to her first round of 16 at a major.

But playing an experienced world number world one on centre court at a Grand Slam was a bridge too far.

Sabalenka saved two break points on her opening service game before sealing it with an ace as the pair sized each other up.

But once she had the measure of Mboko, Sabalenka began to assert herself, reeling off winners to score a double break and race through the opening set in 31 minutes.

Mboko, with heavy strapping on her right leg, was broken again to slump 1-0 behind in the second set as she struggled to find any answers.

A double-fault by the Canadian gifted Sabalenka another break to surge 4-1 clear and it appeared all over.

But Mboko pulled back a break then saved two match points to break again and spark the crowd to life.

It went to a tiebreak, where Sabalenka is a master and raced through to bank the win.

She has now won 20 straight Grand Slam tiebreaks to draw level with Novak Djokovic for the most in the Open era.