His arrival prompted much curiosity and raised eyebrows.
Speaking to Optus Sport, Postecoglou understood the need for silverware and thrived on that expectation.
“You don’t go into a role like this sort of kidding yourself about what you’re taking on,” he said. “I was under no illusions I was taking over a massive football club with a massive following and massive expectation but it was what was appealing to me. It’s where I wanted to be.
"I couldn’t do one of these AFL five year plans where I walk in and say ‘You know, look, I’ll build a team in the next five years’. I knew that wouldn’t cut it, and it shouldn't at a club like this.
“The reality of it is, I had to come in here this year and bring success to this football club. This football club can’t go two years without having some sort of silverware.”
In conversation with former Australia goalkeeper Mark Schwarzer, Postecoglou ruled out a return to manage the national team.
During a four-year spell, he led the country to the Asian Cup in 2015 and to the World Cup
Coming into the Celtic position, despite his success in Australia, there was “scepticism” and “conjecture” but it didn’t faze Postecoglou.
"No," he said, “I went past that stage. I had enough of that in Australia. There was nothing I could do in Australia and there were still people questioning my credentials, my ability to coach.
"Every job I have been in has been the same, there's always a little bit of scepticism or conjecture at the start. There was a lot here, not a little, a lot but I am always confident once I start working and get on with it then people will see what I’m trying to do and those kinds of things should fade away if I am effective.”