Novak Djokovic moved into a 10th consecutive U.S. Open semifinal Tuesday as the beneficiary of yet another premature retirement from his opponent this tournament.
A knee injury forced Jo-Wilfried Tsonga to throw in the towel after just two sets, becoming the third opponent who has failed to finish a match against the world's top player through five rounds at Flushing Meadows.
Djokovic held a 6-3, 6-2 lead over Tsonga when the French No. 9 seed required treatment on his left knee and removed himself from the match.
It has been one odd tournament for Djokovic in New York.