Postecoglou is set to unleash his intensive attacking style on Carlo Ancelotti's visitors and see how far it can take his team, who are full of confident after six successive wins in the Scottish Premier League.
Postecoglou always encourages his full-backs to attack, has two attacking central midfielders in front of the creative Callum McGregor and two wingers supporting his centre-forward. And he is not about to change for the visit of Carlo Ancelotti's side.
"There's no point playing football a certain way but when you get an opportunity to measure it against the very best, you shy away from it and kind of go 'you know what, let's just try and limit any sort of damage'," he said.
"That's not really a test because you don't know. You could go out there and limit the damage and you might get a win playing a different way, but have you really tested yourself? I don't think you have.
"When I say test ourselves, that's what I mean, we go out there being the football team we have been to this point. Then you have got a real measure of where we are at.
"If we are short of where we need to be, then we go back, dust ourselves off and get a bit closer next time.
"I have always taken these games as an opportunity to really stamp your own identity on a game and see where it takes you."
Postecoglou feels such certainty will help his players. "I think it's why we have been so consistent," the former Australia head coach said.
"The players have a clear understanding of what we need to do every week, irrespective of the opponent.
"And there are certainly different approaches you can take. There are a million ways you can be successful in a game of football. If we changed our tactics every week, and we were successful, then the players would be expecting that on Tuesday night.
"But they understand what their roles are within the team, how we are going to play. We do that every week, and we do that for a reason, because we want to win games and be successful.
"If I walked in there and said we were going to change our approach, it's not just Tuesday night we will miss an opportunity but further down the track there will be doubts in their minds about why we are actually doing this.
"The reason we play this football is to win, that's it, there is no other reason for this. I love that it's exciting, I love that our supporters love it, I think that's important, but if it wasn't successful I wouldn't do it."
Postecoglou feels the potential benefits of going all in with his philosophy outweigh the risks.
"If there's a system that doesn't give you risk, I would love to hear it," he said.
"But it doesn't exist. Any system you play there is inherent risk but, sometimes, the greater the risk, the greater the opportunity.
"We are trying to do things a little bit differently. We don't want to be like every other team. With that, there is always the possibility you will stumble. That's fine, I have stumbled in the past. The important thing is you dust yourself off and keep going."
Celtic's 29-2 goal difference in seven matches this season has given supporters hope of an upset.
Postecoglou's side recorded a record 9-0 away win over Dundee United and followed that with a 4-0 thrashing of Rangers in their latest cinch Premiership encounter.
And Postecoglou was keen not to "burst people's bubbles" as the Celtic fans prepare for their first Champions League group game in five years.
"I'm glad our supporters are buzzing about it," he said. "That's what we love about the game. Of course my job is to stay even-tempered, so in terms of my expectations and what I am communicating to the players as a group, is what we need to do to keep progressing. That's a different story.
"But I want our supporters to dream of big games and big wins and winning things. That's the role of us as a football club.
"I'm sure they get enough of their bubble bursting in their normal lives on a daily basis. It doesn't need me to tell them not to come here too excited because it might not go well. I don't think that's my role.
"My role is to make sure they come in bouncing and hopefully we send them bouncing out."