Barty, the top seed, recorded a 6-1, 1-6, 6-2 win over the Belarusian in a battle of two Grand Slam winners at Hard Rock Stadium.

The Australian's reward is a meeting with Azarenka's compatriot and seventh seed Aryna Sabalenka, who swept aside Markéta Vondroušová of the Czech Republic 6-1, 6-2.

"Playing against Vika you have to be ready right from the first point," Barty, competing in her first overseas tournament for more than a year because of the coronavirus pandemic, said.

"I felt like I did that well in the first set and she gave me a few cheap errors. 

"Then through the second she lifted her intensity. 

"I probably wasn't sharp enough in those first couple of games to be able to go with her, particularly with new balls. 

"When Vika is ahead and she's a front runner, she's the very best in the world."

Australian Open champion and second seed Naomi Osaka is also through after the Japanese beat Belgium's 16th seed Elise Mertens 6-3, 6-3.

Victory for Osaka saw her earn a 23rd consecutive win in an unbeaten run that included winning last year's US Open and the delayed Australian Open in February.

Osaka will play 23rd seed Maria Sakkari for a place in the semi-finals after the Greek edged out Jessica Pegula of the United States 6-4, 2-6, 7-6.

Ukraine's fifth seed Elina Svitolina also needed three sets to reach the quarter-finals as she fought back to beat ninth seed Petra Kvitová of the Czech Republic 2-6, 7-5, 7-5.

In the men's draw, Argentina's Diego Schwartzmann made light work of Adrian Mannarino of France to seal his spot in the last 16.

Schwartzmann, the fifth seed, won 6-1, 6-4 and will next face American Sebastian Korda, who thrashed Russian 17th seed Aslan Karatsev 6-3, 6-0.

Sixth seed Denis Shapovalov of Canada is also out after he lost 6-3, 7-6 to Hubert Hurkacz of Poland.

The Women's Tennis Association 1000 and Association of Tennis Professionals Masters 1000 tournament continues tomorrow.