By Associated Press Reporter
Published: 06:20 BST, 2 September 2019 | Updated: 06:20 BST, 2 September 2019
Novak Djokovic's US Open title defence came unstuck on Sunday when a nagging shoulder injury forced the world No 1 to retire from his fourth-round match against Stan Wawrinka, prompting a chorus of boos from the crowd at Flushing Meadows.
Wawrinka was leading 6-4 7-5 2-1 when Djokovic decided he could not continue, the pair embracing at the side of the court before the Serb walked off with his head down low but his left thumb stuck high in the air.
'The pain has been constant for weeks now. Some days higher, some days with less intensity, and obviously taking different stuff to kill the pain instantly,' said Djokovic, who has won the US Open three times.
Novak Djokovic called a medical time out to have his shoulder worked on but then pulled out
The US Open defending champion embraced Stan Wawrinka (left) to a chorus of boos
The Swiss star was two sets up and 2-1 up in the third when his opponent threw in the towel
'Sometimes it works, sometimes it doesn't.
'You just know when you know, I guess, when you feel like you're not able to hit the shot anymore.'
After dropping the second set, Djokovic immediately called for medical attention and sat courtside without his shirt on while the trainer gave