(6) Juan Martin Del Potro
The 24-year-old from Argentina has proved himself as one of the few players on the ATP World Tour with a game capable of competing with the 'big four' on a regular basis.
Del Potro remains the only man other than Djokovic, Federer, Nadal and Murray to have won a Grand Slam since 2005 with his victory at the 2009 US Open.
At 6ft 6in, the 'Tower of Tandil' has some of the most potent weapons on the circuit with a simply blistering forehand, a powerful and consistent double-backhand and serve capable of generating big numbers on the speed gun.
Del Potro looked on course to establish himself alongside the sport's elite quartet following his thrilling five-set win over Federer at Flushing Meadows three years ago.
However, instead of pushing on, he was held back by a persistent wrist injury that ensured his 2010 season was something of a write-off as he missed three of the four majors - including the chance to defend his US Open crown.
Having rather felt his way back in 2011, Del Potro rediscovered something like the form that made him a Grand Slam champion last year as he won ATP titles in Marseille, Estoril, Vienna and Basel and picked up a bronze medal at the Olympics after claiming a first career win over Djokovic.
The South American's record at the Australian Open is rather modest with just two quarter-final appearances in six attempts and no fewer than three second-round exits on his CV.
But he comes into the event on the back of a run to the final of the AAMI Classic, where he was beaten by Lleyton Hewitt, and should he hit his stride, has to be viewed as one of the dark horses for the title.