MELBOURNE: An exhausted and emotionally drained Rafa Nadal walked gingerly towards an exercise mat in the players' gym at the Australian Open and collapsed on it in a heap.

Hardly surprising given the 35-year-old had just spent five hours and 24 minutes on the Rod Laver Arena court, bathed in sweat, rallying from two sets down to edge out world number two Daniil Medvedev - an opponent 10 years younger.

He may have had little left in the tank, but after a few minutes on the mat he picked himself up, got on his exercise bike and got on with his cool-down routine.

"(It) has been a very emotional night," Nadal told reporters afterwards, having fought back against the U.S. Open champion to clinch a men's record 21st Grand Slam title.

"Even now I am destroyed, honestly, physically. I can't think much, I can't remember a lot of moments of the match."

Before Sunday, the last time the Spaniard won from a two-set deficit was 15 years ago, and a second Australian Open title was the last thing he had expected, he said.

A couple of months back he was even considering retiring after a foot problem that has troubled him throughout his carrier resurfaced, forcing him to miss a chunk of the 2021 season including Wimbledon, the Olympics and the U.S. Open.

Underprepared and not in the best of health after suffering a bout of COVID-19, Nadal said he did not expect to go all the way at Melbourne Park, where his only previous success came way back in 2009.

Yet he stitched together an 11-match winning streak following his arrival Down Under, outlasting even the top-seeded Medvedev, who beat arguably the greatest hardcourt player ever in Novak Djokovic in straight sets in New York, in an intensely emotional and physical battle.

Nadal lost about 4 kilograms during his five-set battle in the last eight against Denis Shapovalov and under the floodlights on Sunday he sweated profusely from the start - leaving many in the stands wondering if he would even last if the contest went the distance against the supremely fit Russian.

But the Spaniard said he enjoyed the fight.

"I was not ready physically for these kind of battles, honestly. I didn't practice enough to be ready for it," he said.

"But tonight has been very special. I gave it everything that I had inside, believe me. I am, yeah, super, super tired. I even can't celebrate."

Nadal has lost four championship matches on the blue hardcourts at Melbourne Park before, including a couple in the final set, and he was not going to go down without a fight on Sunday.

"I was repeating to myself during the whole match, 'I lost a lot of times here having chances, sometimes I was a little bit unlucky'," he said, adding that his Australian campaign gave him more confidence that he could continue playing.

"I just wanted to keep believing till the end. I just wanted to give myself a chance. Just fight, just keep belief in trying to find a solution.

"Tonight has been unforgettable. I feel very lucky. At the same time I fought a lot and I worked a lot to try to come back to the tour and to give myself a chance to keep playing tennis."