Stan Wawrinka's stay at Wimbledon was a short one.
A three-time major champion and the French Open runner-up just three weeks ago, Wawrinka was bothered by his left knee and lost 6-4, 3-6, 6-4, 6-1 to Daniil Medvedev at Centre Court on Monday in the first round at the All England Club.
Wawrinka was seeded No. 5 and ranked No. 3. Medvedev, a 21-year-old Russian, is ranked 49th and had never won a Grand Slam match.
Wawrinka iced his knee during changeovers and never was able to summon his best tennis. He has won each of the other three major tournaments but has never been past the quarterfinals at Wimbledon. This was his sixth defeat in the first round at the All England Club.
Wawrinka spoke about his knee after the match.
"It's not something new, but something I had in the past, end of last year and also in Australia. ... But since I had that problem, it was the first time I'm playing on grass. Apparently, grass is not the best surface for my knee. I need to figure out exactly what the problem is now, what I'm going to do, and come back on the tennis court [without any pain].
"I need to [check in] with my team, with my doctor, when I come back home. What's sure is that I'm going to take the time I need to feel ready again physically."
In other Day 1 action, Rafael Nadal advanced to the second round.
The fourth-seeded Spaniard, who won his 10th French Open title last month, beat John Millman of Australia 6-1, 6-3, 6-2 on No. 1 Court.
Nadal is a two-time champion at Wimbledon. From 2006 to 2011, he reached the final every year except 2009, when he skipped the grass-court major because of injury.
Besides extending his championship record at the French Open, Nadal also reached the Australian Open this year, losing to Roger Federer.
Also Monday, Nick Kyrgios retired from his first-round match after losing the first two sets.
The 20th-seeded Australian was trailing Pierre-Hugues Herbert of France 6-3, 6-4 when he called for a trainer to work on his left hip. He then decided to stop the match.
"Probably get an MRI tomorrow," Kyrgios said. "Hopefully get an injection or something, do rehab and get healthy, I guess. I can't really do anything. You know, it's just a bit unlucky what happened."
Kyrgios also retired with an injury from his first-round match at Queen's, a Wimbledon warm-up tournament.
"I kind of knew I was in trouble," Kyrgios said. "I have been feeling my hip ever since I fell over at Queen's. Never got it right. I was doing everything I could to help it, but just not enough time."
"He plays great grass-court tennis," Kyrgios said of Herbert. "He serves well. So he's going to do well."
Tommy Haas has played his final match at Wimbledon.
The 39-year-old German, who has announced this season will be his last, lost to Ruben Bemelmans 6-2, 3-6, 6-3, 7-5 in the first round.
Haas was the oldest man in the draw at the All England Club. He reached the semifinals in 2009, losing to Federer, but needed a wild-card to compete this year.
"Growing up, watching one of my idols, Boris Becker, win in '85 and '86, that's when I knew what I wanted to do," Haas said. "Having played on Centre Court a few matches against some great players and reaching a semis here one time and participating 16 times, it's a boy's childhood dream and I'm very thankful to have done it for so long. I'm very pleased."
Denis Shapovalov's argument with the chair umpire about a late call grew into a spat with his opponent during his first-round 6-4, 3-6, 6-3, 7-6 (2) loss to Jerzy Janowicz.
Shapovalov, an 18-year-old Canadian who won the Wimbledon junior title last year, returned Janowicz's serve while down 40-30 and 4-2 in the third set, but was out of place and gestured wildly before driving Janowicz's next volley backhanded into the net.
After Janowicz was awarded the game, Shapovalov protested, with the umpire explaining that there was a late call on the serve.
"What are you doing?" he asked. "It was a foot long. I don't care that it was a late call."
Janowicz then said the serve was on the line, to which Shapovalov responded, "Dude, don't talk to me right now." Janowicz continued to trade words between games, with Shapovalov replying, "Buddy, I'm talking to the ref. Why are you stepping in?"
Shapovalov was making his first main draw appearance at Wimbledon as a wild-card entry.
Two-time semifinalist Jo-Wilfried Tsonga reached the second round. The 12th-seeded Frenchman beat Cameron Norrie of Britain 6-3, 6-2, 6-2.
Ninth-seeded Kei Nishikori and 24th-seeded Sam Querrey also advanced.
Information from The Associated Press and ESPN's Joy Russo was used in this report.