Novak Djokovic was booed off court by some Australian Open fans after retiring injured from his semi-final against Alexander Zverev.
Djokovic, who was bidding for a record-extending 11th title, quit after losing the first set 7-6 (7-5).
The 37-year-old Serb had his upper left leg heavily taped after injuring it in Tuesday's quarter-final win over Carlos Alcaraz.
"I did everything I possibly could do to manage the muscle tear that I had," said Djokovic, who was also aiming for an all-time standalone record of 25 major titles.
"Towards the end of that first set I just started feeling more and more pain.
"It was too much to handle for me at the moment."
After he slapped a volley into the net on set point, seventh seed Djokovic immediately approached Zverev and shook his hand after 80 minutes of play.
He waved to the crowd and gave them a double thumbs up, despite audible boos from some sections inside Rod Laver Arena.
"I knew even if I won the first set, that it's going to be a huge uphill battle for me to stay physically fit enough to stay with him in the rallies for two, three, four hours," added Djokovic.
"I don't think I had that today in the tank."
German second seed Zverev is still bidding for his first Grand Slam title after twice losing in major finals.
In his first Australian Open final, he will face either Italian top seed Jannik Sinner or American 21st seed Ben Shelton.
'Don't boo a player when they are injured'
From the moment Djokovic lunged for a drop-shot towards the end of the first set against Alcaraz and immediately grimaced to his box, there have been questions over his fitness.
Djokovic, as he has on countless occasions in his stellar career, somehow managed to defy the injury to earn a remarkable win against the 21-year-old.
But doubts remained how equipped he would be to play Zverev.
Djokovic had not practised at Melbourne Park since Tuesday night's victory, cancelling a planned hit on Thursday before spending an hour warming up on court shortly before the semi-final.
Djokovic did not practise between matches during his 2023 title run and later revealed he had a 3cm tear in his hamstring.
He also won the 2021 title despite tearing an abdominal muscle in the third round.
"The very first thing I want to say is, please guys, don't boo when a player is injured," said Zverev, addressing the crowd in his on-court interview.
"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.
"He has won this title with an abdominal tear, he has won this title with a hamstring tear.
"If he cannot continue this match, it means he really cannot continue."
BBC