Wawrinka led 6-4 7-5 2-1 when world number one Djokovic, decided to leave the field with a shoulder injury.“I don’t want to talk about my injuries,” Djokovic told reporters. “I’ve said that in the past. I am sticking to that.”
On the other side Roger Federer cruised into the US Open quarter-finals, thrashing 15th seed David Goffin 6-2 6-2 6-0.
French Open champion Barty has been knocked out of the US Open 6-2 6-4 by China’s Wang Qiang in the fourth round.