Novak Djokovic is out of the US Open after retiring from his fourth-round match with Stan Wawrinka.
The Serbian battled a shoulder injury in his second-round win over Juan Ignacio Londero but appeared to suggest his condition had improved after a third-round defeat of Denis Kudla.
However, the world number one was second best throughout against the 2016 champion and called it quits after he dropped his serve to give Wawrinka a 6-4 7-5 2-1 lead in the third.
Wawrinka, who is in pursuit of his fourth major title, will play Daniil Medvedev for a place in the semi-finals.
— US Open Tennis (@usopen) September 2, 2019
Wawrinka made an outstanding start to proceedings, finding immediate success with his backhand, and he struck the opening blow by breaking to take a 3-2 lead.
The Swiss saved a pair of break points in the subsequent game, holding with the help of three successive aces, before a crunching forehand enabled him to wrap up the set.
Djokovic provided an instant response to start the second set as Wawrinka pushed a backhand long.
However, Djokovic was uncharacteristically sloppy on serve and a pair of double faults followed by an incredible backhand around the net post from Wawrinka laid the platform for a break back that came when the Serbian went long himself at the end of a captivating rally.
A love hold from Wawrinka followed and Djokovic then came under further pressure as he was forced to save a break point before completing a difficult hold with a sublime backhand volley.
Wawrinka, by contrast, went another service game without dropping a point, and a stunning backhand return gave him two break points. He only needed one as Djokovic produced a forehand volley lacking both power and placement.
The second set was sealed in similar fashion as Djokovic failed to execute a backhand drop shot. He received treatment on his shoulder before the third, which he started with a confident love hold.
That proved a false dawn, though, as Wawrinka responded with a comfortable hold before a break to love came his way with a Djokovic double fault that prompted the 16-time grand slam champion to cross the net and shake hands.
Stan Wawrinka  bt Novak Djokovic  6-4 7-5 2-1 ret.
Wawrinka – 17/19
Djokovic – 15/35
Wawrinka – 9/3
Djokovic – 2/5
BREAK POINTS WON
Wawrinka – 4/7
Djokovic – 1/5
FIRST SERVE PERCENTAGE
Wawrinka – 54
Djokovic – 60
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Wawrinka – 84/56
Djokovic – 70/41
Wawrinka – 80
Djokovic – 63