It took a single conversation to make up Ange Postecoglou’s mind.

“From the moment I spoke to him, I knew he’d do for me,” he recalled. “I finished off the Zoom call and said to somebody: ‘he’s going to do well here.’”

On the other end of the call was Alistair Johnston, and, so far, he’s proving the Celtic manager dead right. The Canadian right-back was named man of the match in Saturday’s 3-2 win over Rangers, and is a player seemingly custom-made for such occasions.

Fast, strong, supremely confident and with the talent to match, Johnston has been a revelation from the minute he walked through the door at Celtic Park back in January. So convinced was he of his character, Postecoglou did not hesitate to throw him straight into December’s derby at Ibrox, after which Johnston admitted revelling in the ‘toxicity’ of it all.

“He loves a battle,” said Postecoglou. “I guess he loves these kind of games. When you try and bring in players, particularly to this football club, what I have found is that aside from their abilities as a footballer it takes certain types of characters.

“He’s just a winner, he’s very determined to get the best out of his football ability. He’s embraced the culture here and embraced the responsibility he has.

“You know, in four months he’s had three of these games, three derbies, and I think he’s excelled in all of them.”

No player arrives in Glasgow without pressure on their shoulders, but Johnston had the added stress of following Josip Juranovic, a player whose profile had risen considerably at the Qatar World Cup before he departed for Union Berlin in the Bundesliga.

It seemingly has not bothered him one bit. Even at his unveiling at Celtic Park, there were clues as to why Postecoglou had been so taken by Johnston. Chest puffed out, he carried himself with obvious assuredness, and spoke at length with impressive maturity for a 24-year-old entering a world of scrutiny and attention far beyond anything he could hope to experience in Major League Soccer.

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Signed from CF Montreal for £3m, he has fitted seamlessly into an ultra-competitive group, playing almost every minute amid back-up right-back Anthony Ralston’s recent fitness issues. Postecoglou is excited for what is still to come from Johnston.

“Josip was fantastic for us and contributed greatly,” the manager said. “But Alistair took on that challenge. Tony Ralston has had an injury so he’s our only one so we had to get that right. But I was really confident in him, both as a player and as a person.

“You know what, I think there is still more to come from him. But a big part of that is that you know that the improvement in his football will be accompanied by the fact he’s just the right kind of character in a group.

“He’s not the shy, retiring type. He enjoys the battle and he’s come into an environment where the other guys are like minded.

“We have an outstanding leader in Callum McGregor. But outside of that they all take the responsibility upon themselves and nobody out there needs too much direction.

“They are all prepared to take things on the front-foot when it’s their turn. And he certainly does that.”

Johnston is perhaps the strongest example yet of Postecoglou’s policy of prioritising personality as much as footballing ability. He was left bemused last week by Hibs manager Lee Johnson casually pondering when wiping the floor with the rest of the Premiership becomes ‘too easy’.

You get the distinct impression he would like to ask his managerial counterpart which aspect of being expected to win week after week seems straightforward to him. That demand is, he says, why he pays such attention to the character traits he is signing.

It can seem like a cliché at times, but there are numerous examples down the years where certain players have struggled to come to terms with the pressure of representing Glasgow’s two biggest clubs. Some have even admitted as much after leaving.

It feels fair to say getting it right in this department has been a significant factor in Postecoglou’s success to date.

“It’s hard sometimes to judge when are talking about people’s character and personality,” he said. “But it’s something I work really hard on myself. You are driven to bring in, not just very good footballers, but also good people with the right kind of character.

“People who will embrace the challenges, that when you play for this football club you are expected to win every single week.

“There aren’t many football clubs around the world like that. I know people think it’s easy to do. But I can tell you it’s not.

“It’s very, very demanding that every week there are those expectations. And you need people who want that and embrace that.

“It’s a big part in the type of players we’re bringing to the football club.”

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Those players have now won 29 of their last 30 Premiership matches, and have not lost a domestic home game since January 2021. Few would contend they reached their maximum in Saturday’s derby, yet they still managed to find a way to win.

Yes, Rangers may have hammered the self-destruct button in the second-half, but Postecoglou believes it is no accident his team continue to clear whatever hurdles are put in their way.

“There is just a great spirit and a real, strong self-belief within the group,” he said. “Whatever the challenge is, they’ll find a way to overcome it.

“You don’t have a run like ours if it’s just about the football.  It’s got to be something more than that.

“There have been some brilliant football teams in Scotland and at this football club.

“But what they have done so far, in terms of performance and results, has matched that. And the only way you get to that point is if you have that spirit within the group.”