Roger Federer clinched an 18th grand slam title with an enthralling five-set win over Rafael Nadal in an Australian Open final for the ages.

The dream clash between the two greats lived up to all expectations on Rod Laver Arena before Federer closed out a 6-4 3-6 6-1 3-6 6-3 win on Sunday.

Federer, who with his victory pushed four ahead of Nadal for majors won, was the aggressor throughout and reaped his reward.

The Swiss maestro secured victory in three hours and 37 minutes for his fifth title in Melbourne and first since 2010.

It also helped him improve on a poor record against Nadal in major finals, having now won three of their nine meetings on the biggest stages in tennis, and his triumph is even more astounding considering he missed six months of 2016 with a knee injury, an absence that meant he was 17th seed in Melbourne.

While Nadal tried his usual strategy of targeting the Federer backhand with his trademark fierce forehand, the 35-year-old managed to dictate more points, many of which he wanted to keep short.

A 14-time grand slam champion, this was Nadal's chance to close the gap on his rival, but instead it widened and perhaps ended once and for all the conversation regarding the greatest of all-time.

The epic 2009 final between the duo was decided in Nadal's favour by a poor final set from Federer, but this edition saw both players step up in a thrilling and other-worldly fifth that was deservedly won by the Swiss.

Just five points were won against serve in the opening six games of the first set on a pleasant Melbourne evening, before an aggressive Federer broke.

With a suspected leg injury, Federer needed the first set, and he proved untouchable on serve to close it out in 34 minutes.

But Nadal went 4-0 up in the second as Federer's level dropped and, although he did manage to get one of those breaks back, the Spaniard squared the match.

Federer almost gave up serve inexplicably from 40-0 up in the opening game of the third set, but put on a show after holding.

He took a 2-0 lead with three forehand winners, including an incredible shot down the line to set up a break point he converted.

The momentum, so heavily in Federer's favour to start the fourth, swung again as Nadal broke for 3-1.

Nadal was challenged in the next game before playing arguably the shot of the tournament with an outrageous squash-like forehand cross-court winner to go 4-1 up, a return that cleared the net much to the disbelief of Federer and the Rod Laver Arena crowd.

As the match approached its fourth hour, Nadal forced a deciding set by holding to love, and Federer took an off-court medical timeout.

The break did nothing to slow Nadal, who broke in the opening game of the fifth when Federer sent a forehand wide.

Nadal kept being challenged and Federer's pressure would eventually pay off, a backhand cross-court winner followed by an error from the Spaniard finally seeing him break back for 3-3.

After winning an extraordinary 26-shot rally with a forehand winner down the line, Federer remarkably broke again in the eighth game.

Momentum threatened to swing again as Federer went 15-40 down when serving for the title, but he recovered to secure a famous victory with a forehand winner, the celebrations delayed by a Nadal challenge that would prove incorrect, prompting a raucous ovation from the crowd.

STATISTICAL BREAKDOWN 

Federer [17] bt Nadal [9] 6-4 3-6 6-1 3-6 6-3

WINNERS/UNFORCED ERRORS   
Federer – 73/57
Nadal – 35/28

ACES   
Federer – 20
Nadal – 4

BREAK POINTS WON   
Federer – 6/20
Nadal – 4/17

FIRST SERVE PERCENTAGE   
Federer – 62
Nadal – 73

PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE   
Federer – 76/49
Nadal – 63/56

TOTAL POINTS   
Federer – 150
Nadal – 139