Novak Djokovic has retired from his Australian Open semifinal against Alexander Zverev after losing the first set in a tiebreak. Djokovic missed a regulation putaway volley on top of the net down 5-6,

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 hard to watch the way Jannik Sinner plays tennis and not think of Novak Djokovic. Of all the praise bestowed on Sinner after he won his second consecutive Australian Open championship, and third Grand Slam title overall,