Tennis: Roger Federer wins 20th Grand Slam title with win at Australian Open

Roger Federer celebrates a sixth Australian Open triumph. Photo / Getty

Roger Federer is suddenly within sight of the grand slam title record after entering uncharted waters with a historic sixth Australian Open triumph.

The insatiable Swiss became the first man ever to capture 20 grand slam singles crowns with a fighting 6-2 6-7 (5-7) 6-3 3-6 6-1 victory over Marin Cilic in Sunday night's championship decider at Melbourne Park.

Playing under a closed roof at Rod Laver Arena after officials controversially invoked the extreme heat policy, Federer repelled Cilic's tenacious mid-match challenge to repeat his 2017 Wimbledon final success over the Croat and match Novak Djokovic and Roy Emerson with six titles in Australia.

Incredibly, Federer - despite turning 37 this year - has now won 25 of his 26 matches at the majors since hobbling off Wimbledon's hallowed centre court 18 months ago with a serious knee injury, his playing future uncertain.

But after enduring a four-and-a-half-year grand slam title drought, Federer's remarkable renaissance, at an age when most players are long retired, has netted him three slams in 12 months.

With Laver believing the former world No.1 is playing as well as ever, Federer's relentless run has raised the prospect of the ageless maestro reeling in Serena Williams' open-era record of 23 grand slam singles titles.

If he can defend his Wimbledon crown - which he won last year without dropping a set - and salute for a sixth time in New York, Federer will return to Melbourne in 2019 gunning for grand slam No.23.

Laver doubts Federer would be thinking that way, but suspects the veteran has a window of another year to 18 months to keep piling up the slams.

"He's certainly playing as well as he did eight or 10 years ago," Laver told AAP on Sunday.

Largely untroubled all fortnight, Federer is the oldest Australian Open champion in 46 years after defending the title he won so spectacularly in 2017 following six months out of the game.

Often untouchable indoors, Federer rolled through the opening set in 24 minutes, conceding only two points on serve as Cilic made a nervy, error-filled start to his third grand slam final.

There was no sign of the tension and drama to come, even after Cilic - the 2014 US Open champion - nabbed the second set in a tiebreaker.

Federer seemed to have wrestled back control after taking the third set with a decisive break in the sixth game and then charging ahead 2-0 in the fourth.

But after missing a chance to go up a double break, Federer's serve deserted him as Cilic roared back from the brink to level the final at two sets apiece.

With the final on a knife-edge, Federer fended off a further two break points in the opening game of the deciding set.

But, after dodging the bullets, he broke Croat for a fifth and sixth time to regain his stranglehold on the match before closing it out after three hours and three minutes.

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