Australian Open: Novak Djokovic booed off after withdrawing from semi-final against Alexander Zverev

Novak Djokovic left Rod Laver Arena to a chorus of boos after dramatically pulling the plug on his Australian Open campaign a set into his semi-final against Alexander Zverev.

There had been doubt about the Serbian's fitness until he took to the court after he suffered a left leg injury during his quarter-final against Carlos Alcaraz on Tuesday.

Djokovic did not practise on site on Wednesday then cancelled a session on Thursday, warming up only shortly before the match.

The 37-year-old had heavy strapping on his thigh but appeared to be moving well, sprinting to the net during the first game after a Zverev shot flicked the net.

A cagey set full of long rallies saw both men have chances to break, with Zverev unable to take five break points across two games but recovering from 0-40 in the fourth game.

It was nip and tuck in the tie-break as well until Djokovic netted an easy volley at 5-6 to hand Zverev the set after 80 minutes.

It seemed like the contest was just getting started, but instead Djokovic headed straight to Zverev to shake hands before walking off court to a mixture of jeers and cheers.

The German, who will play in a third grand slam final as he continues to chase a first title, immediately jumped to his opponent's defence, saying: "The very first thing I want to say is please don't boo a player when he goes out injured.

"I know that everybody paid for tickets but Novak Djokovic is somebody that has given this sport for the past 20 years absolutely everything of his life.

"He has won his tournament with an abdominal tear, won this tournament with a hamstring tear, if he feels he can't continue a tennis match, he can't continue a tennis match."

Zverev admitted he was as surprised as the crowd to see Djokovic throw in the towel, saying: "I thought it was quite a high level first set. Of course, the longer you continue, the worse it can get and maybe he was not moving as well in the tie-break.

"Of course, I'm happy to be in the final of the Australian Open but, on the other hand, there's no guy on the tour that I respect more than Novak. Whenever I've struggled, I could call him, ask him for advice. I wanted it to be a tough five-set match as well."

Djokovic's withdrawal means a premature end to his first tournament with coach Andy Murray and it remains to be seen whether the arrangement will continue.