Scott McDonald has admitted he was not fully convinced Ange Postecoglou would be a success when he first took the Celtic job.

The former Parkhead striker, who played for the club between 2007-2010, has always rated his fellow Australian's coaching ability but was unsure whether there would be a personality clash.

He highlighted how the 57-year-old can be "cold" with his players sometimes, which is a feeling McDonald experienced while being coached by Postecoglou when he played for Australia's U20s.

However, the ex-forward now feels that the Hoops boss must have fostered a balanced and effective mindset in the dressing room given the success he has brought to the club.

He told the Off The Record podcast: "If truth be told, I questioned it in terms of his ability, not as a coach but as a person to be able to give players the amount of time they needed for them to believe in who he is at a club like Celtic.

"Ange was always very cold with his players. (He’s) not warming and doesn’t really speak to them but I genuinely believe he wasn’t like that when he first went through the doors at Celtic.

"He had to give more. But with the experience he has gained and the amount of knowledge he has - and the amount of winning he’s had - he’s not a stupid man.

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"He understands and he knew what he had to do. Now he can step back. He’s earned that right.

"Everyone knows who he is and he’s got their respect now. He doesn’t need to walk through the door and talk to Callum (McGregor) every day, but I’ll bet you he was during the first period.

"He would have been talking to the important ones, making sure they bought in and understood what he needed, what he wanted, and that was the thing that surprised the most.

"That’s what I had questioned. It wasn’t about tactics or his knowledge. He’s an excellent football tactician and manager and that has developed since his Brisbane Roar days, then going to the national team and Yokohama, and then coming into Celtic and doing what he’s doing.

“But on that human basis, could he get players to buy into what he was? It shows you what a special character, manager and leader that he is, that he was able to do that and more with this group.

"It’s another special period for Celtic with him in charge at the moment. He’s still as cold and ruthless as ever. He’ll never lose that.

"He’s very cutting when he needs to be. He will not be messed around."