Ange Postecoglou quickly made himself a Celtic hero during an unstoppable period in charge at Parkhead.
But it's the off-field impact of life in Scotland that has stuck with him even after moving to Tottenham Hotspur.
Postecoglou has revealed he revelled in the intense rivalry in Glasgow with even Amazon delivery workers making their feelings clear during his time in Scotland.
Referencing the passion between Celtic fans or rival supporters, he said: "Being Celtic manager for a couple of years, there was only really one result that the supporters were really interested in.
"You got that sense pretty much every time I opened my door. I could tell whether the Amazon guy was a Rangers or Celtic supporter depending on how he delivered the package.
"He either threw it at me or he wanted a selfie. I love that, it's the passion it brings out.
"People feel like their football club is an extension of their family and want to protect that, and want to make sure every week when we go into battle we come out victors, particularly against our rivals."
The Greek-Australian manager has enjoyed a flying start to life at Spurs with his side second in the Premier League with four wins and a draw from the opening five fixtures.
But a major test will come this weekend as Tottenham take on rivals Arsenal at the Emirates.
Discussing the upcoming derby at a Tottenham question and answer session, he said: "It's a great test for us as a group, particularly away from home, looking forward to it.
"We want to be involved in the big games and overcome the challenges before us."
