Tennis legends Rafael Nadal and Roger Federer moved a step further towards their potential semifinal clash in men's singles, while fourth-seeded Kiki Bertens had to retire from women's singles second round citing illness here on Wednesday.

Nadal eased past Germany's Yannick Maden 6-1, 6-2, 6-4, setting up a third round clash with No. 27 seed David Goffin.

"In the third set, I lost a little bit concentration and intensity. Then all the match became difficult," Nadal told a press conference. "The positive thing is every time that I had the mistake, then I had the break again, and that's good news."

Federer also notched a comfortable victory, as the 20-time Grand Slam winner beat another German player Oscar Otte 6-4, 6-3, 6-4.

Greek sixth-seeded talent Stefanos Tsitsipas and No. 7 seed Kei Nishikori of Japan had to recover from one set down to overcome their respective opponents for the third round.

Grigor Dimitrov underwent a five-set thriller to see off 11th-seeded Marin Cilic 6-7 (3), 6-4, 4-6, 7-6 (2), 6-3.

Bertens hoped to build on her recent momentum on clay for Roland Garros title contention, but that was ended by unexpected illness as she had to retire trailing at 1-3 in the opening set.

"This morning I woke up at 3:00, and then I felt really sick. Vomiting, diarrhea all night long and all day long," Bertens explained.

"I felt a little bit better before the match. I just wanted to give it a try, but then as soon as I start warming up right before the match, it started again," she said, adding that "there was not any energy left."

Second-seeded Karolina Pliskova got past Kristina Kucova 6-2, 6-2. The ninth seed Elina Svitolina advanced by walkover from fellow Ukrainian Kateryna Kozlova. Last year's finalist Sloane Stephens and the 2016 champion Garbine Muguruza also found a way through the second set.

Zhang Shuai lost to Estonian veteran Kaia Kanepi, leaving Wang Qiang the only active Chinese player in the draw. Wang will face the 17-year-old Iga Swiatek of Poland in Thursday's second round action.

"She is a really great player. Today I have tried my best. The match may be my best on clay in the last few years. Kaia played really well with good serves," said Zhang.

Zhang somewhat made redemption on doubles court afterwards, triumphing mixed doubles opener with Australian partner John Peers over French pair Margot Yerolymos and Gregoire Barrere 6-2, 7-5.

China also saw two women's pairings into the doubles second round.