Roger Federer
Federer is seeking his 20th grand slam title in Melbourne. Getty Images

Defending champion Roger Federer has warned rivals for the Australian Open that he has arrived in Melbourne in better physical shape than when he won the title 12 months ago.

The Swiss beat Rafael Nadal in five sets to claim his fifth title Down Under, his first grand slam appearance after missing the second half of 2016 with a knee problem.

Federer went on to win his 19th grand slam title at Wimbledon and finished the season as world number two, but conceded matching his achievements during 2017 will be impossible.

But the 36-year-old will at least start the campaign in better condition than last year, having spent the preceding six months sidelined.

"I definitely think I'm in a safer place if you will," he said, according Channel 9. "Last year expectations were not there and it was just about being happy to be in Australia.

"I said before the tournament any result is a good one, so long as I don't get hurt. It ended up being a fairy tale run of winning the entire thing."

Last year's runner-up Nadal, the ATP World Tour Finals champion Grigor Dimitrov and 2016 winner Stan Wawrinka represent the greatest threats to Federer when the opening major of the season gets under way from Monday (15 January).

Much will also be expected of controversial home favourite Nick Kyrgios, who warmed up for the event with victory at the Brisbane International last week – his first tournament win in his native Australia.

The 22-year-old endured an up-and-down 2017 with injury plaguing the middle part of the campaign, while he also admitted to 'tanking' during matches and stated he is not committed to improving his game.

But Federer has much respect for the right-hander. Though he cannot face Kyrgios until the final should both players reach that stage, he believes he could be a threat.

"I think he's actually a really nice guy," added the 2014 Davis Cup winner, who faces Aljaz Bedene in round one. "I know he's got a bit of a mixed image for some people.

"I think he's incredibly talented – we had a great match in Miami this last year and also at the Laver Cup.

"He's a great guy – he's going through the things, whatever he needs to go through. But when he's on, he's on, and he's really difficult to beat."