Novak Djokovic rounded on his critics on Saturday the day after retiring injured in his Australian Open semi-final after the first set against Alexander Zverev to boos from the crowd at the tournament he has won 10 times.

The Serb put on an inspired performance to beat Carlos Alcaraz in the quarter-finals but could not continue on Friday after losing the opener 7-6(5) to Zverev, drawing jeers from some sections of the crowd at Rod Laver Arena.

The former world number one responded on Saturday, posting a photo of an MRI taken of his left hamstring on the social media platform X with the caption: "Thought I'd leave this here for all the sports injury 'experts' out there."

It was not immediately clear from the image what diagnosis Djokovic received.

It was the second time in a year that an injury had derailed the 24-times major winner's Grand Slam campaign after he pulled out of the French Open with a knee problem before the quarter-final stage.

German Zverev defended seventh seed Djokovic in his on-court interview, pointing to the Serb's track record of playing through pain, including winning the tournament in 2021 with an abdominal tear.

"I know everyone paid for tickets and wants to see a five-set match but you have to understand Novak Djokovic is someone who has given absolutely everything to tennis," said second seed Zverev, who plays Italy's top-ranked defending champion Jannik Sinner in Sunday's final as he bids for a maiden major title.

"If he cannot continue this match, it means he really cannot continue."