Alexei Popyrin has braved the hottest conditions he has ever played in to beat Swiss veteran Stan Wawrinka and set up a third-round meeting with defending Olympic tennis champion Alexander Zverev.

Popyrin, the only Australian left in the singles draw, triumphed 6-4, 7-5 on Tuesday in temperatures hitting the high 30s at Roland Garros.

"I think it's probably one of the hottest conditions I've ever played in — and I'm from Australia, so that's saying something," smiled the Sydneysider.

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"But it was really nice. Really good to get the win, and the crowd was amazing. 

The win makes Popyrin the first Australian man since tennis team captain Lleyton Hewitt at the 2012 London Games to reach the third round of an Olympic tournament.

"That's pretty good. It's actually kind of special that he's also here helping me out," Popyrin said.

"I dedicate this win to my team also. It's a lot of work put in behind the scenes. It's really helped me out these last two weeks and we're not done yet.

"I've played him (Zverev) twice before and I know it's not going to be easy. 

"I haven't beaten him, haven't gotten a set off him in two matches. 

"He's one of the best in the world, so it's going to be a tough match for sure."

It was the 24-year-old Popyrin's second straight win over three-time grand slam champion Wawrinka, after beating the 2015 Roland Garros winner in Croatia last year to claim his second singles title.

The world number 63 did plenty of damage with his big serve while also blasting 14 forehand winners to secure the victory inside 90 minutes.

German Zverev downed Czech Tomas Machac in their second-round clash 6-3, 7-5.

The world number four won 88 per cent (14/16) of his first-serve points in the first set and then rallied from a break down in the second set to advance after one hour, 35 minutes.

Zverev, who struck 24 winners, won the gold medal in singles at the Tokyo Olympics in 2021, beating Novak Djokovic en route.

Popyrin and Alex DeMinaur also represented Australia in the men's doubles, but were bundled out in the first round by American pair Austin Krajicek and Rajeev Ram. 

But it has not been all bad news for Australia's pairings, with the veteran combination of Matt Ebden and John Peers defeating Spain's Marcel Granollers and Pablo Carreno-Busta 6-2, 7-5 to reach the quarter-finals.

Ebden, 36, is also in the last eight of the mixed doubles event with Ellen Perez as he continues to make handsome progress following his drubbing in the singles by Novak Djokovic.

But Ajla Tomljanovic and Olivia Gadecki were knocked out of the women's doubles 6-3, 2-6, 10-6 by Russian pair Diana Shnaider and Mirra Andreeva.

AAP