Melbourne: Strutting, chest-thumping Novak Djokovic last year produced one of the greatest seasons in tennis history, and he has signalled his intent for 2012 with an astonishing Australian Open win.

For so long the nearly man, the 24-year-old outlasted the toughest battler in the world, Rafael Nadal, in the longest ever grand slam final which finished in Melbourne in the early hours of Monday.

Seemingly set for victory when leading by two sets to one and dominating, Djokovic was forced to dig deep after the Spaniard fought back to level the match, taking it to a dramatic deciding set.

The win means Djokovic becomes just the fifth player in open era history to win three straight grand slam titles, and the man he has beaten each time is Nadal, the owner of 10 majors.

Djokovic has now beaten the Spanish world number two in seven consecutive title matches, but this win more than any other proves he has the stomach for the fight and the strength to stay at the top.

All the talk is of tennis's "Big Four" but with 30-year-old Federer now regularly failing to reach grand slam finals and Andy Murray yet to win one, Djokovic currently has the edge.

Formerly the joker of the locker room, the Serb, who grew up in conflict-hit Belgrade, transformed his career after a makeover which included dropping gluten from his diet.

Djokovic's dramatic 2011 season left commentators short of superlatives as the Serb won a total of 10 titles and went on a 41-match winning streak, not losing a match until June. He won a record prize money haul of $12.6 million.

Before the Australian Open final against Nadal he spoke of his rivals at the top of the men's game, saying he had worked in the off-season to prepare for another assault on the major prizes.

"Obviously there is Rafa, Roger, and Andy (Murray) who have been probably my biggest rivals in the last couple of years," he said.

"I managed to get to the number one place, win a couple of grand slams last year, and have the best year of my career.

"I'm aware now that everyone wants to win the major titles, get that number one spot. It's normal. It's something I'm prepared for. I've been working hard in the off-season."

The question is whether he can repeat his phenomenal form of 2011 this year.

Some of the gloss was taken off Djokovic's 2011 season with late season defeats as injuries inevitably caught up with him.

The Serb, who now has five grand slam titles, sometimes looked uncomfortable in Melbourne, struggling with his breathing and admitted after his semi-final win over Murray that he had been having trouble with an allergy.

There have been question-marks in the past over the durability of Djokovic, nicknamed "Nole", after he withdrew from the 2007 Wimbledon semi-finals and the 2009 quarter-finals in Melbourne.

But now he has made a habit of digging himself out of trouble. And if ever there was a definitive statement of intent, it was the one delivered against Nadal at Melbourne Park.