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.

Zverev will face defending Australian Open champion and No. 1 seed Jannik Sinner, who beat American Ben Shelton 7-6 (2), 6-2, 6-2, in Sunday's final. Zverev is pursuing his first major tournament title.

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