Australian Open: Novak Djokovic medically retires after first set in semifinal vs. Alexander Zverev
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). It's the first time Djokovic has ever retired in a major.