Novak Djokovic entered the United States Open as the defending champion and No. 1 seed, having won four of the previous five Grand Slam tournaments. It seemed as if there was only a short list of opponents who could stop him from winning his 17th major title.
But he also entered the event with a sore left shoulder, and that proved to be his undoing.
Djokovic retired from his fourth-round match against No. 23 Stan Wawrinka on Sunday because of the shoulder, which made him look like a clumsy, ineffective player rather than the sometimes invincible star he can be when healthy.
“Very frustrating,” Djokovic said. “Obviously not the first, not the last player to get injured and to withdraw from one of the biggest events in sport. But obviously, I just came off the court, so of course it hurts.”
Wawrinka, who was the last player to beat Djokovic at the U.S. Open, in the 2016 final, was leading Sunday by 6-4, 7-5, 2-1 when Djokovic stopped the match.
It is the first time Djokovic, a three-time Open champion, has lost before the semifinal stage of the tournament since 2006, when he was 19. Wawrinka, seeded No. 23, will play No. 5 Daniil Medvedev in the quarterfinals.
After the last game, Djokovic shook his head, then walked over to Wawrinka, who gave his old friend and rival a hug. But as Djokovic walked off the court, the fans, who expected a long match, booed.
“It’s never the way you want to finish a match,” Wawrinka said in an on-court interview. “I feel sorry for Novak. He’s is a good friend and a great champion.”
Djokovic waved to the fans and gave a thumbs-up sign. He demonstrated grace afterward when asked about the jeering.
“Look, I’m not being offended by, you know, mistreated by anybody,” he said. “I don’t really pay too much attention on that. You know, I like to respect others. I hope that others can respect me and my decision.
“I’m sorry for the crowd. Obviously they came to see a full match, and just wasn’t to be. That’s all it is. I mean, a lot of people didn’t know what’s happening, so you cannot blame them.”
With Djokovic out, the remaining players can feel fortified that they will not have to face the best player on tour. One of those is No. 3 Roger Federer, who lost to Djokovic in a thrilling Wimbledon final in July. Federer, who has not won the U.S. Open since 2008, beat No. 15 David Goffin earlier on Sunday and will play unseeded Grigor Dimitrov in a quarterfinal. He now has a potential path through the Open that no longer includes the possibility of facing Djokovic in the semifinals.
Before the tournament began Djokovic said the shoulder bothered him on backhands and on the toss of his serve. The injury probably accounted for many of his 35 unforced errors in the abbreviated match. He received some treatment for it during Sunday’s encounter with Wawrinka.
In 2016, Wawrinka beat Djokovic in a tough, four-set U.S. Open final, the last of Wawrinka’s three Grand Slam titles. A knee injury and surgery in 2017 hampered him the last few years, and his ranking fell to No. 263 in 2018.
But he worked his way back and entered 2019 ranked No. 66 and improved steadily, reaching the quarterfinal stage at the French Open, where he lost to Federer in four sets.
On Sunday, he played as if he would have beaten a healthy Djokovic, especially with his overpowering serve. Wawrinka won 84 percent of the points on his first serve, and he also broke Djokovic’s serve four times to advance to the quarterfinal stage at the Open for the first time since he won it in 2016.