Alexander Zverev slammed the centre court crowd after Novak Djokovic was booed off after retiring in their Australian Open semi-final.

The Serbian superstar suffered a hamstring strain in his quarter-final win over Carlos Alcaraz and finished the match with the help of strapping and painkillers.

The 10-time champion here did not train in the last two days but still entered the Rod Laver Arena to take on the German in pursuit of a record 25th Grand Slam singles title.

The 81-minute first set went to a tiebreak with no breaks of service. But when Djokovic put a forehand volley into the net on the first set point, he shocked Zverev and the crowd by shaking his opponent's hand and announcing he could not carry on.

British chair umpire James Keothavong said: “Ladies and gentlemen, unfortunately, due to injury, Mr Djokovic cannot continue to play.”

The Olympic champion quickly left court - and turned to give a thumbs up to the crowd but booes rang around the Rod Laver Arena.

And in his courtside interview, Zverev said: "Please, guys, don't boo a player who leaves the court due to injury. I know that everyone paid to be here and hopes to see a great five-set match. But you have to understand that Novak Djokovic has given his all to this sport for 20 years.

"There is no one I respect more on the tour than Novak. I have always been able to send him a message, call him when things were not going well. He has helped me a lot. Last year in Shanghai, when things were really not going well after the US Open, we talked for hours."

In his first Australian Open final, the No.2 seed will face the winner of the second semi-final between defending champion Jannik Sinner and American left-hander Ben Shelton