While his players expressed confidence in their form on the eve of their Brisbane clash, the Italian coach cited the Socceroos' experience and focus as significant threats
The Samurai Blue got off to a good start in Asia's Group B with convincing wins against Oman and Jordan, and would take a commanding lead in the standings with a win over the Socceroos on Tuesday.
"The abilities of their players don't stand out; their unity as a team is their strength," Zaccheroni said of Australia during his press conference on Monday evening.
"They have many players with a lot of experience and they know how to accomplish the goals they set for themselves.
"Their coach [Holger Osieck] has also been with the team for a while so he's on the same wavelength as his players."
The Italian also shed light on the status of centre-back Yasuyuki Konno, who missed Monday's practice.
"He's had a cold for the last couple days and we decided it would be best to rest him," Zaccheroni explained.
"Right now we're assuming he'll be able to play, but if he can't I have confidence in [Masahiko] Inoha, [Yuzo] Kurihara, and [Hideto] Takahashi to fill in."
Meanwhile, attacking midfielder Keisuke Honda called for his team-mates to show confidence as they look to improve on their poor recent away performances.
"We have to play our Japanese style of football without being timid," Honda told reporters after Sunday's practice session. "It's a new challenge for us, and to play away in Australia holds a lot of significance.
"We have to play in our arena, not theirs. I want to come back to Japan satisfied with our performance."