Top seed Novak Djokovic was drawn against a qualifier or lucky loser to begin his bid for an 11th Australian Open crown, and could meet fellow Grand Slam champion Andy Murray in the third round, when the draws were made on Thursday.
The Serbian, who has won 24 majors, defeated Stefanos Tsitsipas in last year's final then added the French and US Open titles to his collection.
But the 36-year-old will begin his defence under an injury cloud after a wrist problem hampered him at the United Cup, where he lost to Australian Alex De Minaur.
Greek seventh seed Tsitsipas has a tough task to repeat his 2023 feat with former top 10 Italian Matteo Berrettini his opening opponent and Djokovic a potential quarter-finalist.
Spanish world No 2 Carlos Alcaraz, the only man to beat Djokovic at a Slam last year to win Wimbledon, gets his campaign under way against French veteran Richard Gasquet.
Like Djokovic, third seed Daniil Medvedev, a Melbourne finalist in 2021 and 2022, drew a qualifier in the first round.
The Russian could face 27th seed Felix Auger-Aliassime in the third round, with the Canadian facing a stern opening test against former world No 3 Dominic Thiem.
On the women's side, Polish top seed Iga Swiatek will open her account with a blockbuster rematch of the 2020 Roland Garros final that she won against Sofia Kenin, who went into that match as the Australian Open champion.
There will be no let-up for whoever wins, with a second round clash looming against either 2016 Australian Open winner Angelique Kerber or 2022 Melbourne Park finalist Danielle Collins.
Two-time champion Naomi Osaka also faces a daunting task after being pitted against French 16th seed Caroline Garcia in her first major since having a baby.
Another bumper showdown will see third seed Elena Rybakina, last year's runner-up, take on former world No 1 Karolina Pliskova.
Second seed and defending champion Aryna Sabalenka should have an easier time, she was drawn against a qualifier.
