Ange Postecoglou responded to an unexpected curveball on referees' allegiances as he met fan media on Friday.
The new Celtic boss was officially unveiled as he took questions alongside chief executive Dominic McKay.
Postecoglou met with mainstream media outlets before the club held a separate Q&A with supporters at Celtic Park.
The first attendee to speak to the manager opted not to ask a question, but to urge the 55-year-old to stand up against perceived officiating bias in favour of "one team".
The fan said: "Hi Ange, welcome to Celtic, you'll find that you're at the best football club in the world.
"The people you were speaking to upstairs are not your friends. The people here are your friends and there are a lot more of us and we'll always be with you.
"But please be straight with us and be honest with us at all times.
"We can take defeat but we don't like being cheated and we don't like being let down in the way we have been in the last 12 months, certainly.
"There's referees in this country who support one team, the compliance officer supports one team.
"Penalties for one team, three retrospective red cards last season.
"Look at these things, don't do what Tony Mowbray did and take it on the chin. He did that and it that was an open goal that was exploited and he didn't last very long.
"So, please, the Celtic support are with you and what you said up the stairs about "mixed"... it was never mixed about you, Ange. It was never mixed about you.
"Right away, the Celtic support find out everything they could about you.
"I've not met or spoken to anyone who is not 100 per cent behind you, and also Dom.
"So, the very best of luck. It's not really a question, but there you go."
Postecoglou listened along before vowing that he would always defend the interests of the club, no matter what.
He said: "I appreciate it and what I will say is I will always, always protect the interests of this football club. Always, against anybody.
"I can assure you I won't let anyone take advantage of this football club. My interests lie here so I will protect it with everything I can."
