efe-epaNew York City, USA

World no. 1 Novak Djokovic retired in the third set of his fourth-round match at the US Open against the Swiss Stan Wawrinka on Sunday while trailing 4-6, 5-7, 1-2 and after one hour and 46 minutes.

The Serb, who was nagged by problems with his left shoulder, was competitive in the first two sets and even took a 4-1 lead in the second. EFE-EPA