It is not an issue of running.  “I don’t think under Erik [ten Hag] the team could have done any more running in training,” one Manchester United official tells i.

“There would be all kinds of intense running drills,” another adds. “But what Ruben is trying is maybe a different kind of fitness.”

One game into his United restoration project, Ruben Amorim is already aware of the greatest obstacle to his chances of success in England.

Pressing from the front, as a unit, at an elevated level of intensity is integral to the Amorim modus operandi. On Sunday, as he waved his players forward time and again to pressure Ipswich players into making a pass under at least some duress, Amorim spent more energy instructing his charges than those on the receiving end of the messages.

Amorim could not believe it when Rasmus Hojlund jogged around aimlessly, as Ipswich goalkeeper Arijanet Muric was able to consider his options for what would have seemed, to the new United boss, like an eternity.

Casemiro was equally reluctant, like a nervous teenager at a school disco, glancing back at an animated Amorim on the bench in the hope he had stopped trying to push the Brazilian onto an Ipswich centre-half. There was no such withdrawal.

As Amorim trudged off the Portman Road pitch, he seemed lost in his own thoughts.

“We will have to suffer for a long time,” was his assessment after Sunday’s reality check. While the “Smiling One” may come across as one of the more likeable coaches in world football, there is one area he will simply not compromise.

“When we were together at Sporting, I would tell Ruben that a certain player had too many skin folds,” one of Amorim’s former coaches at Sporting Lisbon tells i. “If he had what we agreed were too many, that player would not play for two weeks, until they got their fitness back up.”

Skin folds tests are a method for estimating body-fat percentage, one which can be administered with a simple pinch between the fingers.

Top-level clubs don’t really have unfit players, not given the dieticians, physicians, personal trainers and yoga instructors in place to provide additional support to the vigorous fitness drills.

While Amorim won’t be going round the Carrington dressing room pinching Bruno Fernandes’ midriff, to be able to pressurise like he wants his teams to, the Portuguese will be hoping to raise the standards among the squad, helping them realise that being able to run for 90 minutes alone is not enough.

His players must be at optimum physicality at all times. That means as well as endurance, they must be able to morph into short, sharp, pressing monsters when instructed.

During training games, in which Amorim, unlike many of his predecessors, plays a very hands-on role, he will shout “ball lost” in the middle of move, and players, in all positions, must sprint back into position, as fast as possible, without losing their formational shape or awareness of where the ball is.

It may sound simple – Manchester City and Liverpool have mastered the craft – but as standards have slipped at Old Trafford, so has the desire and hunger to put teams on the back foot as soon as they are in possession.

“It is not punishment, banning players with too many skin folds,” the Sporting coach continues. “It is about getting standards across, to young players learning what it takes, and older ones who may have forgotten. It is one of many ways we found that extra level.”

Ten Hag was renowned for his intense running session. After a particularly lacklustre display against Brentford early on in his tenure, he brought his struggling players in, on their day off, and had them running eight-and-a-half miles.

The ability to keep going at less than full pelt clearly was not a problem. But the ability to quickly close down defenders in possession was.

“It’s not technical or tactical,” the coach adds. “But being so obsessed with players being at their optimal fitness levels is something that helps you discover who has the desire and character to succeed. You have to want it to get there [the top].

“It is not something people see, but does not make it less important.”

Except in Manchester, the revolution will be televised. While Ten Hag hated having the cameras present at training, as it would enable opponents to get an insight into how he sets his teams up, Amorim and his staff, one insider said, are “much more relaxed” when it comes to opening the Carrington gates to the media: “They don’t seem to care at all.”

It is almost as if the new boss wants everyone to see that one of the most expensive-assembled squads in history will be put through its paces, in an altogether different way to before.