The 24-time major champion and 10-time Australian Open winner lost the first set of his semi-final clash against Alexander Zverev after failing to put a fairly standard volley winner away as it caught the top of the net.

After an epic 81-minute set, fans were just getting comfortable as a five-hour-plus epic appeared on the cards.

But instead of heading to his seat to prepare for the second set, Djokovic went to Zverev, hugging the German to concede the match.

Djokovic, who has played through an abdominal tear and a hamstring tear to win the tournament in the past, suffered another leg injury against Carlos Alcaraz in their quarter-final clash.

After suffering it early in the match before coming back from a set down to win in four sets, there were plenty of questions about whether it was a tactic rather than an actual injury.

The world got its answer on Friday afternoon.

Love him or hate him, there’s no doubt the 37-year-old is one of the most resilient players ever to grace the tennis court and his longevity and fitness is nothing short of superhuman.

Hopefully it’s not the last time we see Novak Djokovic. Photo by DAVID GRAY / AFP

So when certain sections of the Melbourne Park crowd decided this moment was the best time to boo Djokovic as he waved farewell to the crowd, tennis legend John McEnroe couldn’t believe it.

“They can’t possibly be booing him — please,” McEnroe said on Channel 9.

“He’s won this 10 times for god’s sakes. Unreal.”

Australian fans have been getting into trouble for booing players and being overly parochial for our local hopes for years now.

American Danielle Collins made herself public enemy No. 1 at Melbourne Park earlier in the tournament after baiting the crowd in her second round win over local star Destanee Aiava.

And there are countless other instances in recent years.

But it was clear it went too far after Zverev used the first part of his on-court interview to reprimand the crowd.

“Please, guys — don’t boo a player when he goes out with injury,” Zverev said.

“I know everyone paid for tickets and everybody wants to see a great five-set match. But you have to understand for the past 20 years, Novak Djokovic has given tennis absolutely everything.

“He has won this tournament with an abdominal tear, a hamstring tear. If he cannot continue with this match, it means he really can’t continue.”

Djokovic had been struggling. Picture: Michael Klein

The world was in shock over the scenes. Photo by DAVID GRAY / AFP

But the scenes left a bad taste in the mouth with McEnroe, John Millman and Jelena Dokic hitting out at the ugly scenes after the match.

“He’s won this 10 times — I mean, come on,” McEnroe said. “Clearly something was up. The guy’s a battler — him and Rafa have dug deeper than any two players I have ever seen mentally, physically, you name it.

“So to do that when he decided he couldn’t go on after what he’s done here, I thought was absolutely ludicrous honestly.

“That was almost as depressing as seeing him end the match, to see him do that and then put his thumbs-up … too bad, too bad.”

Equally, Millman took aim at the local crowd, saying they’d gone too far.

“The crowds have been questioned a lot and rightly so,” Millman said. “I just think it’s a bit of a shambles, some of the behaviour has crossed the line and that one takes the cake for me.

“This is a guy who has won it 10 times, have some respect. He is one of the greatest of all time, if not the greatest — he’s definitely the greatest on this court. I don’t care how much you’ve paid for your ticket, have some respect.”

Djokovic did everything he could. Photo by DAVID GRAY / AFP

Dokic agreed that Djokovic has showed time and time again throughout his career that he wouldn’t withdraw lightly.

“If he decided he couldn’t play, he couldn’t play,” she said.

Speaking with reporters in the post-match press conference, Djokovic revealed he had to roll the dice in playing after suffering a muscle tear.

“Until an hour before today’s match, I did everything I possibly could to manage the muscle tear that I had,” Djokovic told reporters.

“Medications and the strap and the physio work helped to some extent today.

“But towards the end of that first set, I just started feeling more and more pain, and it was too much for me to handle for me at the moment. So, unfortunate ending, but I tried.”