Stanislas Wawrinka defeated an injured Rafael Nadal 6-3 6-2 3-6 6-3 in a dramatic Australian Open final to win his first grand slam title.
Wawrinka was a huge underdog having never won a set in 12 previous matches against Nadal, but he played superbly to break that sequence and was in control of the second when the world number one suffered a back injury.
Remarkably Nadal managed to win the third set but Wawrinka eventually got his focus back in the fourth to clinch victory.
Pete Sampras had been expecting to mark Nadal's equalling of his 14 grand slam titles but instead the American presented the trophy to a disbelieving Wawrinka.
The Swiss is the first man to beat Novak Djokovic and Nadal at the same grand slam, and turning to the Spaniard he said: "I'm really sorry for you and I hope your back is going to be fine.
"You're a really great guy, a good friend and an amazing champion. It's always a pleasure to play with you.
"Last year I lost a crazy match and I was crying a lot. I still don't know if I'm dreaming but we'll see tomorrow morning."
Nadal had hoped to become the first man in the Open era to win every grand slam title at least twice, but that will have to wait.
The 27-year-old said: "Many thanks to Stan, you really deserve it and I'm very happy for you. We have a great relationship. Bad luck was against me today but you really deserve this.
"It's been a very emotional two weeks and I'm sorry to finish this way. I tried very, very hard.
"Last year was a very tough moment when I didn't have the chance to be playing here. Playing this year has been one of the most emotional tournaments in my career."
Although Nadal's injury inevitably overshadowed the match, there was certainly no guarantee he would have fared any better fully fit.
Wawrinka thrived as the underdog and adopted an ultra aggressive approach, which brought dividends with a break in the third game.
The occasion seemed to get to him for the first time when he served for the first set and Nadal brought up three break points.
But the world number one failed to make a return off three second serves and Wawrinka ended his 26-set losing streak against Nadal with an ace.
There was no let-up at the start of the second and by the time a run of 12 straight points came to an end, he was already a break ahead.
It was while Nadal was serving to get on the board in the third game that he appeared to suffer the injury.
He winced, held his back and doubled over in pain before leaving the court for a lengthy medical time-out.
Wawrinka was furious that he was not being told what the injury was and entered into a heated debate with referee Wayne McKewen.
When Nadal came back on court he was loudly jeered by the Rod Laver Arena crowd, but the problem was all too apparent.
He was rolling in serves at less than 80mph and moving very stiffly on the baseline, while the emotion was clear to see as he struggled to hold back tears.
It was rough luck for Nadal, who said on Friday after beating Roger Federer how happy he was to be fit - blister aside - and have a chance to challenge again for the Australian Open title.
It has been a troublesome event for the Spaniard, who was hampered by injuries in 2010 and 2011 and missed last year's event because of knee problems.
The crowd was back on Nadal's side as he saved three set points to hold for 2-5, but the Spaniard sat with head in hands at the changeover, sending the trainer away.
It was a mental test for Wawrinka, whose head must have been spinning, but four big serves gave him the set.
Nadal appeared to think about calling it a day at the end of the set but decided to head to his chair, and his decision was validated at the start of the third.
Wawrinka was struggling to deal mentally with the situation, and a combination of that and a slight improvement in Nadal's movement helped him into a 3-0 lead.
The turmoil in Wawrinka's head was apparent when he made two poor mistakes on break points and, somehow, Nadal clinched the set.
Wawrinka was battling himself more than his opponent, and two more break points went begging at the start of the fourth, a set he desperately needed to win.
But the Swiss was handling events much better now, holding his own serve easily, and he finally broke Nadal to lead 4-2.
Incredibly, he was then broken back to love, but Nadal's serve was still his big weakness and Wawrinka struck once more to move to within a game of victory.
This time he held his serve to love, raising his hands in delight and relief, although his muted celebrations reflected the strange circumstances of his maiden grand slam triumph.
Wawrinka becomes only the second man after Juan Martin del Potro to break the big four's stranglehold on slam titles since Marat Safin won the Australian Open in 2005.