MELBOURNE • Back where his comeback began last year, Roger Federer continued to rewrite his remarkable script yesterday with what was previously thought an unattainable 20th Grand Slam title.

The Swiss defending champion dropped his only sets of the Australian Open before completing a 6-2, 6-7 (5-7), 6-3, 3-6, 6-1 win over Marin Cilic in 3hr 3min.

"I'm so happy it's unbelievable. This is a dream come true, the fairy tale continues for me," Federer said at the trophy presentation as wife Mirka and Australian great Rod Laver recorded the moment with their mobile phones. "After the great year last year, it's incredible."

At 36 years and 173 days old, he became the oldest winner of the title since Ken Rosewall 46 years ago.

Federer also joined Novak Djokovic and Roy Emerson as the only men to win six Australian Open trophies.

But he is peerless in the list of all-time men's Grand Slam winners - four ahead of Rafael Nadal, six in front of Pete Sampras and eight more than Djokovic.

"It is a different emotion, clearly. The first (Grand Slam title) is like, 'Oh my god! I was able to win one'. The rest now doesn't really matter at this point," Federer said at Melbourne Park, where he ended a five-year major drought 12 months ago.

"This one here tonight reminded me more of maybe the 2006 win when I beat (Marcos) Baghdatis in the final. I had a great run to the final (in 2006) and was a huge favourite going in.

"I was just so relieved when everything was said and done (and) I think I felt the same way tonight. That is why I couldn't speak (at the presentation), it was terrible."

Only three women - Steffi Graf (22), Serena Williams (23), and Margaret Court (24) - have been crowned champion at more Slams.

Federer grabbed the first set in just 24 minutes. But Cilic did not allow his first Australian Open final to go by in a flash. Despite fighting a lone battle against Federer and most of the crowd, the sixth seed reeled off five consecutive games in the fourth set to extend the champion into a deciding set.

Federer had to save two break points in an epic service game at the start of the fifth set before riding the momentum home as Cilic's power game wavered.

The Croat later attributed his slow start to the roof closure on Rod Laver Arena due to hot weather.

"I didn't feel those conditions before," said the 29-year-old.

"I had a slow start in the match, losing straightaway my two service games, then catching up most of the time."

The organisers can only activate the tournament's extreme heat policy and call matches off or shut the roof when the temperature is 40 deg C and the wet bulb globe temperature index hits 32.5 deg C.

The temperature was 37 deg C when Cilic and Federer took to the court. When the umpire called time to commence the match, the wet bulb temperature was 32.6 deg C.

Former Wimbledon champion Pat Cash was among those who criticised the decision to close the roof, which he felt favoured Federer.

Organisers defended the decision after Simona Halep was hospitalised for four hours with dehydration following her women's final defeat by Caroline Wozniacki.

AGENCE FRANCE-PRESSE, REUTERS