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.

An injured Novak Djokovic has quit after dropping the first set of his Australian Open semifinal against Alexander Zverev.

Zverev won a grueling first set in a 7–6 tiebreaker that lasted one hour and 20 minutes. Djokovic decided he couldn't continue with a left leg injury that was hindering him throughout the match. The 10-time Australian Open champion revealed afterward that the injury was a muscle tear.