By Shrivathsa Sridhar MELBOURNE (Reuters) -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.

An ailing leg leads to an abrupt finish for the 24-time major winner, who’s a 10-time winner in Melbourne.

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.