Roger Federer advances at Wimbledon when Adrian Mannarino retires due to injury after slipping on grass

Mannarino retires vs. Federer after nasty slip (1:27)

Adrian Mannarino withdraws in the fifth set, allowing Roger Federer to advance at Wimbledon. (1:27)

Roger Federer survived a tough opening-round test at Wimbledon on Tuesday, advancing via walkover after his opponent, Frenchman Adrian Mannarino, was injured while holding a lead of two sets to one and retired a few games later.

Mannarino, playing on his 33rd birthday, won the second and third sets before withdrawing with a leg injury. He was behind 4-2 in the fourth set when he slipped on the slick grass and fell, grabbing his right knee in pain. He limped through two more games before reluctantly calling it quits on the second point of the fifth set. The score: 6-4, 6-7 (3), 3-6, 6-2.

Federer was sheepish about winning.

"Not like this, please," he told the crowd. "Look, he could have won the match at the end. Obviously he was the better player."

An erratic forehand plagued Federer, and he flirted with losing in the opening round at a Grand Slam for the first time since 2003. He committed four unforced errors with his forehand in the tiebreaker alone, including a shank.

Even so, the eight-time Wimbledon champion improved to 7-0 against Mannarino.

In the match that followed on Centre Court, Serena Williams was forced to retire in the first set due to injury when she slipped near the same spot Mannarino did.

Federer surely articulated a common sentiment when told by a reporter what happened to Williams. "Oh, my God," he said. "I can't believe it.''

Novak Djokovic fell twice in the first set of his first-round victory Monday in the main stadium, too.

Rain interrupted play for the second day in a row, but matches continued on the two courts with retractable roofs.

"I do feel it feels a tad more slippery, maybe, under the roof," Federer said. "I don't know if it's just a gut feeling. You do have to move very, very carefully out there. If you push too hard in the wrong moments, you do go down. I do feel it's drier during the day. With the wind and all that stuff, it takes the moist out of the grass. But this is obviously terrible."

The All England Club said in a statement Tuesday that the wettest two opening days of Wimbledon "in almost a decade'' indirectly led to "additional moisture'' on the grass at Centre Court while the retractable roof has been closed for long periods.

Wimbledon was canceled in 2020 because of the pandemic. The courts were removed and new grass installed, as happens after each tournament.

The club's statement read: "The preparation of the grass courts has been to exactly the same meticulous standard as in previous years.''

The Centre Court has been roof closed "for long periods'' due to showers on Days 1 and 2 this week, "at a time when the grass plant is at its most lush and green, which does result in additional moisture on what is a natural surface,'' the statement said, adding: "With each match that is played, the courts will continue to firm up.''

Earlier Tuesday, Alexander Zverev had 20 aces and only 18 unforced errors as he swept qualifier Tallon Griekspoor in the first round, 6-3, 6-4, 6-1. The result was a big improvement for Zverev after losing to a qualifier at Wimbledon in 2018 and 2019.

Zverev is seeded fourth but is only 9-5 at the All England Club.

Zhizhen Zhang, the first man to represent China in the main draw at Wimbledon during the Open era, was beaten by Antoine Hoang of France, 4-6, 7-6 (5), 6-7 (5), 6-3, 6-2.

In the final set, Zhang struggled with his serve, while Hoang had an 11-4 edge in winners. Zhang, 24, won three matches to qualify. He failed in three previous attempts to qualify at Grand Slam tournaments.

Sebastian Korda, 20, made his Wimbledon debut and upset No. 15-seeded Alex de Minaur 6-3, 6-4, 6-7 (5), 7-6 (5).

Korda is ranked a career-high 50th, and he added momentum to his breakout year by beating a top-20 player at a Grand Slam for the first time. De Minaur, a 22-year-old Australian, was coming off his first tour-level grass title at Eastbourne.

No. 2 Daniil Medvedev, No. 9 Diego Schwartzman, No. 10 Denis Shapovalov and No. 26 Fabio Fognini also advanced on Day 2.

The last match being contested Tuesday night, between Nick Kyrgios and No. 21 seed Ugo Humbert, was suspended at 3-all in the fifth set because local rules prevent play past 11 p.m.

Kyrgios and Humbert -- who also played an entertaining five-setter at the Australian Open in February -- were playing on No. 1 Court, which has a retractable roof and artificial lights.

Kyrgios won the first and fourth sets Tuesday; Humbert took the second and third.

The Associated Press contributed to this report.