The Swiss, 35, won 6-4 3-6 6-1 3-6 6-3 to claim his fifth Melbourne title.

"For me it's all about the comeback, about an epic match with Rafa again," he said. "The last problem is the Slam count. Honestly, it doesn't matter.

"We're going to party like rock stars tonight. I can tell you that."

Five years after his last major victory at Wimbledon, and 10 years since he beat Nadal in a Grand Slam final, Federer finally clinched title number 18 with a thrilling five-set victory.

The victory came in his first tournament back following six months out with a knee injury, which he picked up when running a bath for his children at last year's Australian Open.

It appeared as though another Grand Slam opportunity was slipping away when Nadal took the fourth set and then moved 3-1 up in the decider.

However, Federer came storming back with five games in a row and a brilliant display of attacking tennis.

"I told myself to play free," he said.

"That's what we discussed with [coaches] Ivan [Ljubicic] and Severin [Luthi] before the matches. You play the ball, you don't play the opponent.

"Be free in your head, be free in your shots, go for it. The brave will be rewarded here. I didn't want to go down just making shots, seeing forehands rain down on me from Rafa. I think it was the right decision at the right time."

The victory makes Federer the first man to win three of the four Grand Slam titles at least five times each - but it was his lone victory at the French Open in 2009 that was in his thoughts on Sunday.

"I can't compare this one to any other one except for maybe the French Open in '09," he said.

"I waited for the French Open, I tried, I fought. I tried again and failed. Eventually I made it. This feels similar."