(3) Roger Federer
The Swiss maestro shows no signs of slowing down despite heading into his 17th season on the ATP World Tour.
Federer reaffirmed his status as the game's 'greatest' in 2012 with a 17th Grand Slam at Wimbledon before returning to the top of the world rankings, albeit briefly.
He heads to Melbourne Park seeded second at an event he has won four times, but only once in his last five visits.
Since his straight-sets demolition of Andy Murray in the 2010 final, Federer was been on the receiving end of convincing semi-final defeats to Novak Djokovic and Rafael Nadal in each of the last two years and will be keen to set the record straight.
Curiously, though, the 31-year-old opted to skip his traditional warm-up events in the Middle East and has not played a competitive tournament since losing to Djokovic in the final of the ATP World Tour Finals back in November.
After playing only a handful of exhibition matches, Federer will be aiming to replicate Djokovic's feat from 12 months ago by winning the Australian Open having not played a warm-up tournament.
For the Swiss, the weight of history has never proved too problematic but for his critics, and some fans, there are fears that world No.1 Djokovic and US Open champion Murray are now too strong.
But write Federer off at your peril.