Here are five players who might challenge the world's top two Andy Murray and Novak Djokovic for the title.
The tall, serious Canadian ended 2016 as world number three as he continued his steady rise up the rankings, and it is surely only a matter of time before he wins a Grand Slam.
Raonic, 26, laid down a marker for the season at last year's Australian Open when he ousted Stan Wawrinka before falling to Andy Murray in a thrilling five-set semi-final in which he was hampered by injury.
Six months later, he reached his first Grand Slam final at Wimbledon before losing to Murray again.
Raonic rounded off the year with a last-four spot at the ATP World Tour Finals in London and he heads into 2017 with a new coach, former Wimbledon winner Richard Krajicek.
"The Stanimal" is riding high after winning his third major at the US Open and the powerful Swiss has the tools to triumph in Melbourne, as he memorably proved in 2014.
Wawrinka has forced his way into tennis's upper echelons in the past three seasons but now aged 31 faces the challenge of staying there -- and even improving -- as a group of younger players matures.
The world number four with the brutal, one-handed backhand appears to enjoy the conditions at Melbourne Park, and it was a surprise when he lost to Raonic in the last 16 a year ago.
The superlative Swiss has lost none of his popularity but, at 35, only his most ardent fans would rate him as a leading contender for the Australian Open, where he will be making his 69th Grand Slam appearance.
Federer is feeling his way back after a six-month injury lay-off, the longest of his career, which he ended with a mixed performance at the Hopman Cup team tournament in Perth last week.
Federer does not seem to be contemplating retirement, however, and he remains stubbornly optimistic of a last hurrah to add to his record 17 Grand Slam titles.
Federer's ranking has dropped to 17 after his long absence, meaning he faces a tougher draw.
Like Federer, Nadal's aura and results are on the wane and it has been more than two years since he last won a major, at his favoured French Open in 2014.
The 30-year-old Spaniard didn't make it to any of the Grand Slam quarter-finals last season, and his tally of two tournament wins was his lowest in 12 years as he dropped to ninth in the world.
Nadal has won only one of his 14 major titles at the Australian Open, when he beat a tearful Federer in an epic, five-set final in 2009.
He will certainly look to improve on 2016, when he was sent packing by fellow Spanish left-hander Fernando Verdasco in the first round.
Wawrinka dubbed Zverev the "future of tennis" after losing to the German in last year's St Petersburg final, and it is a label that seems apt for the 6ft 6in (1.98 metre) 19-year-old.
Nicknamed "Sascha", he is already ranked 24th, has a string of scalps to his name including two victories over Federer, most recently at the Hopman Cup.
What's missing so far is a deep run at a Grand Slam tournament, and Zverev was unlucky to come up against Murray in the first round in Melbourne last year.
This time around, he will be under close scrutiny for signs that he is making good on his vast potential.