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.

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 retired injured after losing the opening set of his clash with Alexander Zverev on Friday, sending the German to a first Australian Open final where he will take on defending champion Jannik Sinner for a maiden Grand Slam title.