An injured Novak Djokovic quit because of a torn muscle in his left leg after dropping the first set of his Australian Open semifinal against Alexander Zverev on Friday. Djokovic lost the opener 7-6 (5) in a tiebreaker and immediately walked around the net to concede the match to Zverev.

Alexander Zverev chided the crowd after they booed Novak Djokovic for retiring due to injury after the first set in an Australian Open semifinal.

Novak Djokovic is out of the Australian Open in stunning fashion. The 24-time slam champion medically retired immediately after dropping the first set of his semifinal match against No. 2 Alexander Zverev in a tiebreak 7-6 (5).