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.

Djokovic, who retired due to injury after the first set, was booed by the crowd as he walked off Rod Laver Arena.

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.