Nadal has now won three of the four Grand Slam titles
Rafael Nadal produced a display of incredible defiance to beat Roger Federer 7-5 3-6 7-6 (7-3) 3-6 6-2 and win his first Australian Open title.
The Spaniard, 22, recovered from his marathon semi-final to ruin Federer's attempt to equal Pete Sampras's record of 14 Grand Slam titles.
Nadal saved 13 of 19 break points as he refused to yield in a stunning match.
The world number one has now won six Grand Slam titles - including four at the French Open and one at Wimbledon.
He took his record against Federer to 13 wins in 19 matches, and five in seven Grand Slam finals between the pair, in a worthy successor to their last meeting at Wimbledon in July.
Nadal won that match in five sets and, despite playing just two days after winning the longest match in Australian Open history in his five-hour semi-final win over Fernando Verdasco, the top seed prevailed again in another sensational encounter.
With so much at stake it was still a surprise to see Federer, 27, make a desperately nervous start, dropping serve immediately in a woeful game of three wild errors and a double fault.
Nadal had the chance to build an early lead but was pegged back straight away in a 10-minute game, Federer converting his third break point with a smooth forehand winner down the line.
The Swiss moved ahead with another break in game six when he leapt on a short serve, but Nadal stormed back in the following game with a magnificent running forehand and a fierce cross-court backhand before Federer double faulted on break point.
There was plenty of the magic that the world's top two can be relied upon to produce but Federer was a little below par, serving at 54% with 15 unforced errors when Nadal broke again for 6-5 before serving out the set.
I've felt better. God, it's killing me
Federer on defeat
The world number two picked up his form with two spectacular forehand winners for break point in game four of the second set, but Nadal chose the perfect moment to deliver his second ace of the day.
A couple of vicious backhands helped Nadal to a potentially decisive break at 2-2 but this time it was Federer who hit straight back, levelling at 3-3 when the Spaniard went long with a forehand.
Game eight of the second set was a key moment as Federer earned break point four times, and each time Nadal responded - three fantastic serves and a drop shot saving the world number one - before the Swiss converted his fifth chance with a move to the net.
Federer confidently wrapped up his fourth straight game to win a set during which he had served at a lowly 37%, and it had slumped to 35% by the time he faced a break point at 2-3 in the third, saving it with a forehand winner.
Nadal called for the trainer after game seven and had treatment on his right thigh, and two games later looked in desperate trouble at 0-40, but the indomitable Spaniard fought his way out of trouble to stay on serve.
He certainly appeared to be feeling the effects of his semi-final, but again the world number one saved three break points in his next service game.
And an incredible turnaround looked on the cards when Nadal got to set point in game 11 but he could not return a fine Federer serve and a crucial tie-break loomed.
It was as brilliant and dramatic as expected, Nadal edging 5-3 clear before earning three set points with a magnificent lunging backhand volley, and taking the set when Federer, incredibly, double faulted.
Just remember you're a great champion and you're one of the best in history and for sure you're going to match Sampras
Nadal to Federer
Nadal simply would not buckle and after Federer lost an early break advantage in the fourth the set as the Spaniard fought back yet again, the usually implacable Swiss slammed a ball into the advertising boards in frustration.
If anything, the quality of play and drama only heightened at 2-2 when Nadal earned five break points of his own, winning one amazing rally with a forehand that had the crowd on their feet, but this time it was Federer who produced with his back against the wall.
The momentum had swung, for the moment, in the second seed's favour and he capitalised to break for 4-2 before serving out relatively easily.
It did not signal a burst of new-found confidence from the three-time champion, however, and he was the first to crack in the decider, playing a nervous game that included a double fault and two desperate backhands to drop serve in game four.
The errors began to flow from the Federer backhand and a focused Nadal made him pay, moving to the verge of the title with some confident serving.
Two match points arrived when Federer, on serve, hooked a regulation forehand wide but two nervous Nadal errors kept the contest alive.
The Spaniard responded with a blistering cross-court backhand winner onto the line that Federer chose not to challenge, and when the Swiss went long with a forehand a breathtaking match was finally over after four hours 23 minutes.
A tearful Federer struggled to make his runner-up speech afterwards, admitting: "I've felt better. Maybe I'll try later. God, it's killing me."
Nadal, the first Spaniard to win the Australian title, accepted the trophy from Rod Laver and said: "Roger, I know exactly how you feel.
"Just remember you're a great champion and you're one of the best in history and for sure you're going to match Sampras. To receive this trophy from Rod Laver is a dream for me."
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