Last season, Federer ticked the two remaining boxes on his career checklist when he won the French Open for the first time before breaking Pete Sampras's record of Grand Slam men's singles titles.

His biggest challenge now is to maintain his motivation and while Federer insists he remains as keen as ever, the Australian Open could provide the first real glimpse into what lies ahead for his opponents.

Federer has already won the Australian Open three times but is less dominant on the Melbourne Park synthetic hard courts than he is at Wimbledon and the US Open.

By his own lofty standards, his early season form has been patchy. He was beaten by Swede Robin Soderling, for the first time, in Abu Dhabi then lost to Russia's Nikolay Davydenko in another warm-up event in Qatar.

Nadal looms

Despite his uncertain buildup, Federer remains the pre-tournament favourite. After all, he has made the final of 17 of the last 18 Grand Slams, dating back to Wimbledon in 2005.
However, he was beaten in last year's Australian Open final by Rafael Nadal in a five-set classic and the Spaniard once again looms as his biggest obstacle.

Nadal was on top of the world 12 months ago. He had beaten Federer in the finals at the French Open and Wimbledon in 2008 to spirit away the number one ranking then reduced the Swiss to tears by beating him at Melbourne Park.

But in the blink of eye, the aggressive left-hander plummeted back down to earth from his perch when his knees began to buckle and the injuries started to mount up. He took a break from the game and has not won any title since May.

There were some encouraging signs when the world number two helped Spain win the Davis Cup last month then made last week's final in Qatar to give himself a confidence lift.

Serbia's Novak Djokovic won the Australian Open in 2008 to emerge as the most likely challenger to the Federer-Nadal duopoly but has failed to reach any Grand Slam final since while US Open champion Juan Martin del Potro has fitness concerns.
Andy Murray will again carry the weight of expectation of a British public starved of grand slam success.

Exciting times

The presence of Maria Sharapova, Kim Clijsters and Justine Henin  has added even more spice to the women's tournament already overflowing with talent.

Serena Williams is the favourite and understandably so. She is the current world number one, the defending champion and one of the few players who thrive in the scorching Australian summer heat.

Williams has won at Melbourne Park four times but if she is to make it five she will have to interrupt a winning sequence that has seen her take the title in alternate years since 2003.

"This is what I was born to do," she said. "It's what I do best. "I'm just super mentally tough, I feel like that's definitely one of my strengths."

It is no surprise that Serena has flagged her older sister Venus as her biggest threat but the Russians and Belgians present a more formidable challenge.

Three of the world's top five are Russian and there are five in the top 15 including Sharapova, Elena Dementieva, Dinara Safina and Svetlana Kuznetsova.

However, the most intriguing twist is the return of the Belgian pair, Clijsters and Henin, who played each other in the 2004 Australian Open final.