No. 1-ranked Djokovic starts at the top of the draw and will open against a qualifier.
Should Djokovic, a six-time victor at Melbourne Park, beat an as-yet-unknown qualifier, he could face wild card Jo-Wilfried Tsonga in the next match, with Denis Shapovalov a possible third-round opponent and Kei Nishikori potentially awaiting in the last eight. Eighth-seeded Kei Nishikori, who opened the season with a title in Brisbane, is a potential quarterfinal rival and No. 4 Alexander Zverev looms as a semifinal opponent if both players advance that far.
Defending champion Roger Federer is seeded No. 3 after Rafael Nadal, while women's defending singles champion Caroline Wozniacki, who beat Halep in last year's final at Melbourne Park, is No. 3 behind second-seeded and 2016 champion Angelique Kerber.
Defending champion Wozniacki, who broke through for her maiden Grand Slam title with victory over Halep in last year's final, is in line to face former victor Maria Sharapova in a mouth-watering third round showdown.
World No 1 Novak Djokovic is the favourite to take home his 15th Grand Slam title. And with No. 6 Marin Cilic in the same quarter, there's potential for a rematch of the 2018 final a few rounds early.
"I can't believe it's been a year already", Dane Wozniacki said at the draw ceremony.More news: Meghan Markle and Prince Harry's $4.5m temporary farm home
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An exchange followed, with Murray even offering to sort her out a ticket for his first-round match against Roberto Bautista Agut. If it would happen defending this title, I would gladly accept it.
Serena Williams will face Tatjana Maria in the first round, and could meet either Genie Bouchard or Peng Shaui in the second round.
Federer is a six-time champion in Melbourne, and the 37-year-old is targeting a third-straight victory in the opening major of the season.
The pair have met four times in finals at Melbourne Park, with Djokovic winning them all, but those memories made this all the more disappointing.
Halep, however, may be reluctant to look beyond the first round, having drawn her U.S. Open nemesis Kaia Kanepi.
"The hip is incredibly difficult to come back from for especially a tennis player and someone that has worked as hard as he's worked, put the miles on", ESPN tennis pundit Patrick McEnroe said. "I'm just enjoying every minute of it".