In a stunning development at the Australian Open, Novak Djokovic withdrew because of injury after losing the first set of his semifinal match versus Alexander Zverev. Zverev, the No. 2 seed, won a grueling first set in a 7–6 tiebreaker that lasted one hour and 26 minutes.

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).

Spectators booed as the 37-year-old Djokovic walked off toward the locker room, and he stopped, turned around and responded by giving two thumbs-up.