Djokovic sets up semi-final clash with Monfils

Defending champion Novak Djokovic booked a 10th straight US Open semi-final appearance when Jo-Wilfried Tsonga retired trailing 6-3, 6-2 in their marquee quarter-final on Tuesday. It was the third time in five matches that an opponent's injury has worked to Djokovic's advantage, after his walkover into the third round where Mikhail Youzhny retired after just six games.