On Wednesday Postecoglou unveiled his provisional 30-man squad for a pre-tournament training camp and farewell friendly against South Africa, before daunting matches against Chile, the Netherlands and Spain at the tournament itself.
Cahill is one of the most experienced players selected in the group and the New York Red Bulls man can't wait to meet up with his teammates as they prepare to take on the world's best.
"The one thing for me is that if Ange needs you in any sort of tactical way, a bit like what Guus (Hiddink) used (me for) in the first World Cup and a lot of us players in the second World Cup, you have to be ready," he told Fox Sports.
"And it's that one defining moment that can change a game, and that's what I'm looking for. I'm looking for the moment where if you play 90 minutes or 60 minutes, whatever, that every single player in training is ready tactically, mentally and physically to add to it.
"I'm ready to go."
The Socceroos are not expected to escape from what is arguably the toughest of the eight groups in Brazil, but Cahill insisted they are capable of troubling their heavyweight opponents.
"I truly believe that we're going to make a good account of ourselves," he said.
"These next two weeks will help to define us, the way we play. This is also the evolution of a new side being (bred) for the Asian Cup. We're going to go there with no fear. If you get through a group like this, anything is possible."
Although he claimed Australia will seek to go on the front foot in South America, Cahill knows the onus will be on the team to defend for long stretches of their three matches.
"We've still got to be mindful of ... being compact and disciplined," he said.
"And with Ange it starts in training. But not only on the training pitch, every single day, off the park, your attitude and your intent to do well as human being as much as an athlete. Attention to detail is something that he's very good at and I've been very impressed.
"The main thing for me is just to being ready to be in the box or be a help to these youngsters finishing off the good work they're putting in."