Djokovic retired from his Australian Open semi-final after losing the opening set to Alexander Zverev

Djokovic could not play on through the pain and quit the match after the first set as Zverev reached his first Australian Open final

Djokovic is out of the Australian Open after retiring from his semi-final, with Zverev through to play Jannik Sinner or Ben Shelton

The opening grand slam of the season kicks off another blockbuster tennis year