What has been the highlight of Manchester United’s wretched pre-season so far? The signing and growing cult status of third-choice goalkeeper Lee Grant? Axel Tuanzebe breaking the Guinness World Record for the fastest game of Hungry Hungry Hippos? Matteo Darmian’s clearance that killed a bird?

Sadly, even if the tour of the United States had brought a single, genuine cause for optimism, it would have been snuffed out by the narrative surrounding Jose Mourinho and his unhappiness with United’s preparations – a midsummer tiff between a manager and his club that is threatening to spill over into the new season.

Mourinho’s post-match press conference after the 4-1 defeat to Liverpool in Michigan on Saturday made his frustrations clear. This was no furious meltdown, as social media suggested. Instead, it was in keeping with Mourinho’s history of slow, careful and considered complaints, each sentence sharpened to a barb.

Half the players on the tour will “not even belong to our squad” by the start of the season, now just 10 days away, he said. “This is not even half my squad, or 30 per cent of it.” Alexis Sanchez cannot possibly be happy considering “the players he has around him”. United are not using this tour to prepare for the new campaign, he added, they are simply trying to “survive”.

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Most of us are guilty of being pop Mourinhologists, finding double meanings and ulterior motives in his words when there are none, but in Michigan he was unequivocal. His gripes all come down to the club’s lack of transfer business. “I gave a list to my club of five names a few months ago,” he added, ‘my club’ being a metonym for United’s executive vice-chairman Ed Woodward. “I wait to see if it’s possible to have one of these players.”

Ideally he would like two, and unless both a centre-half and a wide player arrive before the transfer window closes on 9 August, Mourinho will carry his bad temper into the new season. Even if Woodward delivers one new player, his manager will still have a genuine grievance to cite if or when United ‘struggle’ at the start of the campaign.

He is right, after all, that the signings of Diogo Dalot, an inexperienced full-back, and Fred, an accomplished midfielder, are unlikely to be enough to challenge Manchester City alone. Those arrivals must be supplemented. Mourinho would also have expected support in this summer’s market when he agreed a new contract at Old Trafford just six months ago, and not unreasonably so.

Yet there are clear and convincing reasons for the club’s reluctance too. Toby Alderweireld, Mourinho’s preferred centre-back target, will be 30-years-old before the season is out. So too Ivan Perisic, the winger Mourinho attempted to convince Woodward to buy last summer and a player he made a point of praising during Croatia’s run to the World Cup final.

There is Mourinho’s recent track record to consider, as well. Another centre-half would be his third in three years. Eric Bailly has shown authority in flashes, but never enough to fully win the trust of his manager. Victor Lindelof has rarely looked as commanding as Bailly and is likely to remain on the fringes of the squad, even if a new centre-half is not found.

There are sound arguments on both sides, ultimately, and a sense that as the deadline nears, the situation will only escalate. Saturday’s comments from Mourinho, more forthright and direct than before, could be read as the first clear battle lines and we should expect more of the same – right up until 9 August, then beyond it – if little progress is made in the market.

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Yet if these difficult few weeks become a difficult few months, and Mourinho does enter a long, dirty, public war with a boardroom once again, he would be wise to make sure he carries enough support to win. He does not, for example, enjoy the total backing of the club’s fanbase, who may sympathise with his complaints of ‘Glazernomic’ penny-pinching but are yet to be won over by his brand of football.

Many are just as ambivalent about him as they are Woodward. This is a manager, after all, who has not shied away from criticising his own supporters. It is hard, at this point, to imagine that “Our Jose” banners would drape around Old Trafford if Mourinho were to be suddenly dismissed, as happened at Stamford Bridge three years ago.

Has he fostered more of those intense professional relationships with his players – like with John Terry and Frank Lampard at Chelsea, or Marco Materazzi​ and Wesley Sneijder at Inter – that help put a dressing room under his spell and inculcate that 'siege mentality' when necessary?

It may not come to that. The club may bend to Mourinho’s will, backing a manager they committed to with January’s contract renewal. Mourinho could even compromise – he has already, of course, by dropping demands for a new left-back.

If not, though, United’s start to the new season will be a stormy one, the ‘struggle’ Mourinho predicted will come and by the end, Tuanzebe’s Hungry Hungry Hippos record may be all they have to show for it.