World number one Rafael Nadal is chasing his fourth consecutive major to complete a 'Rafa Slam', while world number two Roger Federer is bidding for a fifth Australian title.
The first entry lists to be released show Serena Williams and Hungary's 37th-ranked Agnes Szavay both out with injury.
Denmark's Caroline Wozniacki is campaigning for a maiden Grand Slam title to go with her top ranking.
Organisers said the 104 direct acceptances into the men's draw include Argentina's former US Open champion Juan Martin Del Potro and Russian Dmitry Tursunov, who both have used their injury-protected rankings.
"To have the top 104 players in the world in the men's main draw is incredible and shows the high esteem with which the Australian Open is held in world tennis," tournament director Craig Tiley said.
"The women's field also has every available top player in the world. The players vote with their feet and they are doing it again."
The men's field will be completed by 16 qualifiers and eight wildcards, while the women's field has 12 qualifiers and eight wildcards to be added. The Australian Open takes place at Melbourne Park from January 17 to 30.