US Open: Defending champ Djokovic retires against Wawrinka in fourth round

Defending champion and world No. 1 Novak Djokovic was forced to retire with the left shoulder injury in fourth-round U.S. Open match against Stan Wawrinka, on Sunday.

Djokovic was two sets down against 23-seeded Swiss with scores 6-4, 7-5, 2-1, at the Arthur Ashe Stadium, when the 32-year-old Serb walked to the net and threw in the towel following a double-fault.

The two men hugged near the net as the defending champ called off the game, that was Djokovic’s sixth retirement in a major tournament.

“It’s never the way you want to finish a match,” Wawrinka, who beat Djokovic to win the title in New York in 2016, said on court.

“I’m really sorry for Novak. He’s a good friend, he’s an amazing champion, we play amazing battles whole my career. But I want to keep my level tonight. I think I was playing super good tennis. I’m happy to be back.”

This year Djokovic has won four of the last five Grand Slam titles, including the Australian Open and Wimbledon, and has 16 majors for his career.

World No. 1 had struggled with a painful left shoulder during his second-round win over Juan Ignacio Londero. As the defending champ is out of the race to the title and the $3.85 million prize money is even more up for grabs.

Djokovic’s retirement has certainly raised the potential that No. 2 Nadal and No. 3 Roger Federer could meet for the first time in the U.S. Open.

Wawrinka will next face No. 5 Daniil Medvedev in the quarterfinals on the top half of the draw while Federer will be facing Grigor Dimitrov.