Day 6: Three things to look out for

Serena Williams continues her quest for a record-tying 24th Grand Slam title, while contenders Stefanos Tsitsipas and Arnya Sabalenka are both in action as Roland-Garros moves into the third round.

Serena faces test from Collins

Three-time champion Williams will meet a familiar face at Roland-Garros on Friday when she takes on fellow American Danielle Collins in an eagerly anticipated third-round match.

Though the pair have met on court just once, with Williams winning earlier this year in a pre-Australian Open event in Melbourne, the two women are good friends off the court.

>> ORDER OF PLAY: DAY 6

Collins has spoken this week about her recovery from surgery after having endometriosis and Williams said she respected her opponent on and off the court.

“She's been playing well,” Williams said, adding Collins is “also a really awesome person off the court.”

Collins reached the quarter-finals in Paris last October and could present Williams with a big test but the 39-year-old joked that she was more concerned about the court.

“I seem to be getting a lot of bad bounces,” the former top-ranked American said. “I don't understand how to play on this stuff and not get these bad bounces. Maybe you just have to deal with them. Once I deal with them, I'm fine.”

Isner hoping heat will help against Tsitsipas

If Tsitsipas is going to reach the last 16 of Roland-Garros again this year, he’s probably going to have to do something that John Isner’s first two opponents failed to do; find a way to break his serve.

The 2.08m (6’10”) American has not dropped serve in his first two matches and with more time to return, clay is arguably his best surface.

“Most times here at Roland-Garros, these are incredible serving conditions for me,” Isner said. “I don't think people realise how good of a surface clay can be for a guy like myself, especially if the weather for myself is cooperating. If it's 75, 80 degrees and sunny, the ball is bouncing really high and the court is playing pretty fast. It's very, very good conditions for me.

“These conditions out here are really tailor-made for me, I believe. I've played six sets and held serve all six sets, and I hope in a couple days' time it's going to be hot just like it was today.”

Tsitsipas has looked pretty impressive in his first two rounds, cruising through without the loss of a set. But the No. 5 seed could be in for a tough battle against Wimbledon marathon man Isner.

“He's a guy who likes to play on clay,” the Greek said. “Conditions are obviously the way they are. Just going to have to do my thing. Just have to find my way around it.”

Sabalenka ready for Pavlyuchenkova battle

The balls are likely to take a bit of a pounding when two of the biggest hitters on the women’s Tour collide as No.3 seed Sabalenka takes on Pavlyuchenkova.

Sabalenka beat Pavlyuchenkova on her way to the title in Madrid last month and the Belarusian is feeling good about her game as she looks to make her Grand Slam breakthrough.

“She’s a tough opponent,” Sabalenka said of Russia’s Pavlyuchenkova. “She's aggressive. She's playing really well right now, moving well and hitting quite strong balls. I'm really looking forward for this match, for this battle. I will do everything I can to do well there.

“I just need to be really focused. I need to bring my level there to win this match. It's going to be a great fight and I'm really looking forward to it.”