‘Go shock ’em all!’.

Not Ange Postecoglou’s latest rallying call for Celtic but the four-syllable order issued by President Joe Biden to the US national team ahead of the World Cup in Qatar.

Called up by coach Gregg Berhalter, Parkhead defender Cameron Carter-Vickers was caught on camera listening intently as Biden placed a call from the White House to the squad’s base ahead of the greatest sporting show on earth.

Speaking from his desk in the Oval Office, Biden urged the Americans to ruffle a few feathers in the Middle East, a feat they achieved in qualifying for the tournament’s knockout phase.

Privy to the ‘we-never-stop’ mantra championed by his Australian club manager at Lennoxtown, Carter-Vickers was privileged to be among the select audience addressed by the leader of the free world last November.

Asked to compare the Biden call to a Postecoglou pep-talk, the player said: ‘They’re slightly different. I’d say Ange’s probably have a bit more tactical knowledge of football!

‘They are obviously both motivational people who you can take stuff from.

‘We knew the President was going to be on the call when we went into the meeting room and to have someone like that supporting you definitely gives you a boost.’

Biden may be commander-in-chief of the world’s greatest military force but in ‘soccer’ terms, the US remains an underdog.

Picked for his excellent form for Celtic, first on loan from Tottenham and then following a £6million ($7.2m) permanent transfer last summer, Carter-Vickers sat out the first two drawn group matches against Wales and England, before being selected to start against Iran in the all-important third match.

That night in Doha saw the States claim their sole win in the tournament and qualify for the last 16, where they fell to the Netherlands.

Yet that one taste of victory enriched the experience for the defender who, having just turned 25, can reasonably expect another couple of shots at playing on the world’s top stage.

‘It was a great experience,’ he reflects. ‘Just being at the world’s biggest tournament was great for me personally but I also got to play one game. I enjoyed that and I learned from it.

‘There’s a real tight bond between the coaches and players within that group.

‘With a tournament like that, you’re away for four or five weeks as a group and you have to get on with people otherwise it can be a horrible time.

‘The USA group definitely has that — we get on well and socially it’s good.

‘Americans are generally quite patriotic and you definitely saw that with some of the performances at the World Cup.’

Aside from their remote presidential audience, each player in the States squad was commemorated in billboard form prior to the commencement of the competition.

In Carter-Vickers’ case, that meant a roadside message being posted in Baton Rouge, Louisiana, hometown of his father Howard, who was once himself a basketball player of some repute.

‘My dad still lives there,’ continued the defender. ‘I used to spend summers there and I still go over to see him when I can.

‘I have good memories from those days when I was younger, spending time with family. The whole of my dad’s side of the family is over there — cousins, aunties, uncles.

‘They really got into the World Cup. I talk to my dad regularly but he and the rest of the family were watching the games together.

‘The billboards helped build support for the team, it can only be positive and some of them were quite funny.

‘Baton Rouge is quite a big place, so I’m not sure if dad went for a look himself but he said friends and family were sending him pictures.’

Captaining the Americans in Qatar was Leeds United midfielder Tyler Adams, a player who has made a big impression since being brought to Britain by his compatriot Jesse Marsch.

A young skipper at 23, Adams compares favourably to Carter-Vickers’ club captain Callum McGregor, who notched up his 400th appearance for Celtic last weekend.

‘Callum’s a great example to all of us,’ he added. ‘Not just in games but every day at training he always sets the standard.

‘Tyler is similar. Every day you see him 100 per cent at it. He’s good vocally and motivates the team well.

‘I always think as a captain you have to lead by example and both of them certainly do that.’

After the Americans’ elimination in Qatar, Carter-Vickers enjoyed a break before returning to the familiar, gruff tones of Postecoglou.

Celtic’s form since the December resumption has been excellent with a handy draw at Ibrox the closest thing to a blemish on their results sheet.

Sunday sees a return to the scene of one of the season’s stickier moments. Leading against St Johnstone at McDiarmid Park in October as the match entered stoppage-time, Celtic conceded an equaliser to an Alex Mitchell header before summoning the strength to eke out a Giorgos Giakoumakis winner.

Mention of that day leaves Carter-Vickers nonplussed, possibly because the end result simply fell within the normal parameters of the ‘we never stop’ ethos.

‘We’re probably not thinking too much about the last game,’ he said. 'It was a while ago now and we’re confident that if we can play to our level we’ll get the result.’

For much of the first half of the season, Carter-Vickers was denied his usual centre-back partner Carl Starfelt though injury.

In the Swede’s place came Moritz Jenz, a loan signing who started each of the club’s six Champions League matches yet who has since been moved on.

While Yuki Kobayashi has been signed to compete for Starfelt’s left-sided berth, Carter-Vickers appreciates the solidity and security provided by having his long-term sidekick back.

And the results bear out his opinion as together the pair have registered four clean sheets in succession.

He said: ‘I think the more you play with the same player or players around you the better the understanding. You start to know where each other will be without too much communication.

‘It is challenging to be a defender in this team. The demands the manager places on us are high.

‘But I think a lot of our defensive work is helped by our front players as well, the way they press and put pressure on the other team when they have the ball.

‘Carl and I get on well. I think we are similar characters, both really chilled guys.

‘I wouldn’t say either of us is a massive communicator on the pitch. If something needs to be said or there needs to be some organisation, both of us will do it.

‘But we’ve played with each other for a long time now and the way the manager sets us up is quite clear.

‘I think everyone is clear in their mind what their role is defensively as well as going forward. So there isn’t too much communication needed.

‘In general, training is in tight areas and we train the way we play. Things we are asked to do in games we are asked to do every day in training.

‘It’s about repetition really.’

Such repetition makes it hard for Celtic to surprise anyone far less ‘shock ’em all’. But it does make them incredibly hard to beat.