Noel Whelan has fired a warning to Ange Postecoglou - insisting he could be gone by CHRISTMAS if he does not start well at Celtic.

Former Leeds and Aberdeen striker Whelan believes Postecoglou will come in for stick if he fails to impress the Hoops support early doors, with Midtjylland Champions League qualifiers coming up.

The outspoken pundit also reckons the fact that the Australian head coach was only given a one-year rolling contract - like the club have dished out in the past to managers - shows they are not fully convinced by him yet, either.

"There is going to be question marks from the get-go," he told Football Insider. "If he does not hit the ground running he is going to come in for it, simple. That is what happens when you take over at a club like Celtic.

Glasgow Times: Whelan fired a warningWhelan fired a warning

"The fact that the club only gave him a rolling one-year contract speaks volumes. They are not clearly convinced either. If Postecoglou had the full backing of the board he would have been given a three-year contract.

"He has got a lot of work to do to convince the players and to convince the fans.

"If there is a sizeable gap between themselves and Rangers at Christmas time you could see the club start looking for a replacement. It would not surprise me.

"Postecoglou is a relative unknown at the end of the day so he will come under criticism. It was a shock to everybody when he was appointed."

Postecoglou seemed to bristle during his first press conference as Celtic manager when his experience was questioned. Asked if a move to Glasgow would be a step-up for his career he said: "There is no bigger cultural challenge than coaching in a country where you don’t speak the language. I did that in Japan.

"That was a massive challenge for me and I enjoyed it. That’s why I went. Every job has differences but it’s not an enormous leap.

"It’s still football. That’s what I’ve found. When I went to Japan I couldn’t communicate. I had to figure out how I could get my message across some other way and we still did that.

Glasgow Times:

"The team still played the football we wanted, the players responded and we were successful. What I bring is a little bit of a different perspective.

"I’ve had a different journey in football from many others. Most of my experience has been on the other side of the world.

"I bring here what I bring to every organisation I’ve worked with – a clear idea of how I want the team to play and how success comes from that.

"People will be in no doubt about how this team will play its football. Every team I’ve coached has had a real clear identity and it fits nicely with the traditions of this club.

"It’s probably one of the reasons I was chosen because I’ve done that for 25 years.

"It is a massive challenge but as a manager you always get opportunities where there is a massive challenge.

“If I didn’t want pressure I’d probably be doing a different occupation or stayed coaching my local club. But I’m here because this is where I want to be."