On Wednesday morning, Manchester United’s players reported for training and began work on a tactical plan devised by manager Erik ten Hag for the weekend trip to Brentford. Ten Hag’s first fixture in charge, a 2-1 home defeat by Brighton the previous Sunday, had constituted a major setback and he informed his players of two substantial tweaks to his line-up.

The first was to restore ageing superstar Cristiano Ronaldo to the starting line-up after only being on the bench against Brighton, which in turn facilitated the second alteration, which would see new signing Christian Eriksen end his brief, befuddling spell as a false nine and instead operate far deeper as a defensive midfielder.

As such, two positions were tweaked but only one player dropped out of the side beaten at Old Trafford — midfielder Scott McTominay.

Though the tactical plan was laid out on Wednesday, only 10 positions in the line-up were clear to the players at that stage. It was not until the following day that Ten Hag settled on club captain Harry Maguire, rather than 2018 World Cup winner Raphael Varane, as the partner for Lisandro Martinez, another newcomer.

In short, United worked for three full days on how they would overcome one of the few sides in the Premier League they defeated both home and away last season.

It was all pretty extraordinary, therefore, that United ended up 4-0 down inside 35 minutes in a performance their underperforming goalkeeper David de Gea later described as “horrible” and “unacceptable”.

The 45-cap Spain international, who has been at the club for 11 years, insisted on speaking afterwards both to broadcasters and the written media to issue a flurry of apologies. He declared himself culpable for Brentford’s first two goals.

Ten Hag, however, viewed Saturday’s humiliation as a collective affront. He said the United performance offered confirmation of his conclusion last week that he had “a hell of a job” on his hands following a summer switch from serial Dutch champions Ajax.

He admitted in a post-match press conference: “Brentford were more hungry for one, and two, we conceded goals with individual mistakes. You can have a good plan but then you put the plan in the bin.”

He had previously told one international broadcaster his team’s performance had been “rubbish”.

The aftershocks began there in west London on Saturday night and culminated in an aborted day off for the players, a fresh frenzy around Ronaldo’s future, renewed question marks about dressing-room unity, and even more pressure on the club going into the final two weeks of the summer transfer market.

Ten Hag made his feelings known to the players, at half-time and then again at full-time, before informing them that yesterday’s scheduled day off was cancelled.

Instead, the squad, who arrived back home in the Manchester area around 11pm after the trip up from London, were ordered to report to the club’s Carrington training base for 9am Sunday, where Ten Hag’s retribution continued.

The coaching team were embarrassed by statistics that showed United’s players ran a total distance of 95.6km in the match, compared to Brentford’s 109.4km. As such, Ten Hag’s staff set up a session — solely a running session — that required each player, even those who did not start on Saturday, to run near enough the difference of 13.8km between the two teams’ combined distances during this additional training session.

Although many supporters disgruntled by the application of their players may cheer on this hard-line approach, one sports scientist with experience working at rival Premier League clubs described it as old-school and said it is unusual to put players through so rigorous a workout the morning after a late afternoon fixture.

United sources insist their medical and sports science staff would not approve any workout that carried a high risk of injuries, and it is understood a couple of players, owing to the way injuries are managed, were excused.

United’s players had turned out in baking-hot temperatures exceeding 34°C for the game kicking off at 5:30pm on Saturday and yesterday was another warm day in Manchester, although only in the mid-20s in the morning.

Ten Hag clearly wanted to make an emphatic point to his players that there is a way to lose in United colours and he will not tolerate his players being outworked by modest opponents such as Brentford, who finished 13th last season in their first year ever as a Premier League club.

Sources close to the new United manager say his determination has only been enhanced by these early setbacks and that he will challenge the players to improve. Ten Hag also made his feelings clear to his players during several meetings at Carrington following the running session.

Ten Hag ordered his players to undergo a running session after defeat by Brentford (Photo: Getty Images)

Though the mood on Sunday was sombre, multiple sources who represent United players said they had been impressed by the manager’s discipline, attention to detail and methodology since he arrived at the club. The reality, however, is these traits have not translated into performances.

The Athletic asked Brentford head coach Thomas Frank how he instils this elusive hunger in his team.

He said: “We spoke about it before the game but you can’t just say, ‘Oh, can you do it?’. It’s a long strategy and communication. In general, my teams run a lot. We enforce the message that we need to do it. It is also about passing, but if you run more than the opponent, you have a very good chance to win.”

For Ten Hag, the rubble of Saturday’s devastation required further unpacking and he sat down with his inner circle of assistants to ruminate on the best way forward.

Foremost among Ten Hag’s current concerns is the situation around Ronaldo, who missed United’s pre-season tour to Thailand and Australia due to a “family issue”.

Reports emerged to say the 37-year-old forward wished to leave a club he only rejoined last summer after 12 years playing in Spain and Italy due to fears United are unable to meet his ambitions outside of the Champions League — they will play in the Europa League this season after finishing sixth in May — and the sluggish pace of their work in the summer transfer market.

Ronaldo, however, is yet to receive a serious proposal from a Champions League-qualified club, despite attempts by his representatives to seduce Chelsea, Bayern Munich, Napoli, Atletico Madrid and Barcelona.

Ten Hag, meanwhile, initially wanted United to dig in and keep one of the game’s greatest ever players on their books. He took the view that even at such an age, Ronaldo remains a world-class goalscorer they could not afford to lose — he led United with 24 all-competitions goals last season, 14 clear of their next most prolific player.

Ten Hag preferred to devote the bulk of his transfer kitty to reinforcing their defence with the £47million ($57m) signing of Martinez from previous employers Ajax and the £14.4million signing of full-back Tyrell Malacia from Dutch rivals Feyenoord. The club also still have an agreement worth up to £71.9million in place with Barcelona for their Netherlands international ex-Ajax midfielder Frenkie de Jong, if they can persuade the player to reunite with Ten Hag in England.

Yet since returning from United’s tour, which saw good performances and a strong unity develop among the travelling group, Ronaldo’s reintegration into the squad has proven challenging.

The Athletic has been told of days when he eats lunch alone in the canteen at Carrington, and he has been seen flapping his arms about in training and attempting to argue against the high-pressing approach favoured by the new manager. The club and Ronaldo’s representatives were approached for comment.

Several sources close to United, who wished not to be named to protect their business relationships, argued that Ronaldo has been afforded greater leeway than his peers and indulged beyond the contribution he is providing to the club.

United are still to receive any formal interest for Ronaldo but it is now thought Ten Hag would be open to allowing the 189-cap Portugal captain to leave — as long as United recruit in the forward position, where they are painfully short of options.

Ten Hag is open to Ronaldo leaving if United can sign a replacement (Photo: Getty Images)

Ronaldo had further exasperated coaches and supporters when he did not acknowledge United’s travelling fans after the full-time whistle, despite assistant coach Steve McClaren appearing to urge him over to them.

It should be said that Ronaldo did participate in the running drills yesterday morning.

It is not only Ronaldo who has raised eyebrows, with sources close to other players surprised to see reports that Dwaine Rashford, the brother and agent of United forward Marcus Rashford, had met serial French champions Paris Saint-Germain for talks in recent weeks. Rashford’s contract at Old Trafford runs out at the end of this season, although United have an option to extend it a further year.

One ray of light, however, is that striker Anthony Martial, who has missed the opening two matches of the season with a hamstring injury, is now back training with the first team.

As United continue to scour the market for options up front, Atletico Madrid’s Spain international Alvaro Morata, 29, has been presented as an option. They are also considering a move for Jamie Vardy, but Leicester are reluctant to let the 36-year-old former England striker go. United have been linked with Espanyol’s Raul de Tomas, who has scored 45 goals in 89 appearances for the Barcelona club.

Ten Hag’s problems, of course, stretch far beyond Ronaldo’s future, and attention on Saturday turned towards his tactical setup for Brentford, which, as stated earlier, had been three days in the making on the training fields at Carrington.

The most notable individual criticism was directed towards his former Ajax centre-back Martinez, whose 5ft 9in (175cm) height came under scrutiny. Martinez was substituted, along with left-back Luke Shaw and midfielder Fred, at half-time with United already four goals down.

The Argentinian was the one central defender Ten Hag had been sure would start on Wednesday, with Varane and Maguire vying to partner him. By the time the second half began against Brentford, it was Maguire and Varane alongside one another. Ten Hag said he would have had cause to substitute any of his 11 starting players had the option been available.

Brentford goalkeeper David Raya said his team had planned to target a long ball to their powerful striker Ivan Toney, who went up against Martinez.

Raya said: “That was the game plan today — kicking it long, to utilise Ivan’s strengths in the air. We used it the whole game and it paid off.”

Toney himself added: “My qualities in the air is something we worked on. I’m obviously up against a smaller centre-back. It was a good game plan.

“I was just trying to put my body about and get the better of him. To be fair to him, he was doing well. He was very aggressive for a centre-back. Sometimes he gets beat in the air but he was aggressive on the floor. I felt like it was 50-50. Like you said, it’s a compliment to me, him getting subbed off at half-time, whether it was because of me or if it was the style of play they wanted to go for.”

Martinez was a specific target of Ten Hag in this summer’s window, having played the previous three seasons for the Dutch coach at Ajax.

Interestingly, The Athletic has learned United’s scouting network watched numerous Ajax games in recent seasons and despite Martinez often featuring, he was not a player flagged as worthy of closer examination for Ten Hag’s predecessors Ole Gunnar Solskjaer and Ralf Rangnick.

Some scouts were said to be concerned Martinez was a player who could become trapped at set pieces.

One defender the recruitment team did admire, along with Solskjaer, is Spanish side Villarreal’s Pau Torres.

None of this is to say United have definitely erred in signing Martinez, and club sources also insist that once Ten Hag made clear he wanted the 24-year-old South American, a consensus developed on the decision before it was signed off.

Time will tell whether Ten Hag’s judgment is correct.

Similarly, although Malacia impressed for United during pre-season, The Athletic has also heard he was a player Wales specifically sought to target in their game plan — due to his 5ft 7in height and their estimation of his abilities — during two Nations League fixtures against the Netherlands in June.

Brentford also appeared to quickly close down Eriksen, who played for them in the second half of last season as he made his comeback after suffering a cardiac arrest playing for Denmark at the European Championship 14 months ago. Eriksen was pounced upon by the Brentford press ahead of their second goal, and central defender Ben Mee said they targeted United’s attempts to play out from the back.

“Man for man, closing them down,” Mee said of Brentford’s approach. “We knew they would be a bit unsure from the weekend (against Brighton) and maybe lack confidence. With the determination, pace and power we’ve got up front, pressing them, getting in their faces, they didn’t enjoy it all. We made the most of it. When we got those opportunities we scored a couple of goals from it.”

While Ten Hag is applying the stick, there is also a need to imbue this grossly underwhelming team with confidence via a bit of carrot, too.

United conceded four goals in the space of 25 minutes on Saturday and have now lost seven consecutive Premier League away matches stretching back to last season — their worst run since the 1930s. They have not won after going 1-0 down since Michael Carrick was in caretaker charge for a 3-2 victory over Arsenal in early December.

De Gea said: “When something goes wrong, people get panicky. It’s difficult. There is no pressure in pre-season, you play for nothing. Then you play Premier League games, everything is different, teams put everything on the pitch. The teams are good, it’s not easy.”

It reinforces the perception, suggested to The Athletic by multiple sources close to the players, that the atmosphere in the United dressing room lacks both the harmony and accountability of teams such as Liverpool and Manchester City.

Relations between goalkeeper De Gea and centre-back Maguire have appeared strained to some observers, although other training ground sources insist the pair do get along reasonably well during training. There are also elements of the squad who expected Ten Hag to change captain this summer after Maguire’s authority in the dressing room was felt to diminish amid his poor form last season.

Maguire and De Gea are struggling for form (Photo: Naomi Baker/Getty Images)

There is also a feeling United are psychologically scarred by their collective experiences as a team.

Rangnick’s decision to appoint sports psychologist Sascha Lense was immediate when he took interim charge for the rest of last season after Solskjaer was sacked in November but United’s ordeal only intensified and Lense has since departed.

For Ten Hag, therefore, the challenge is evident.

One source close to the new United manager said he is attempting to “build an aeroplane as he flies.”

More turbulence is on the way — the next game is home against arch-rivals Liverpool a week today.

United are still attempting to recruit De Jong and working on adding competition for De Gea and much-needed reinforcements up front.

One player highly unlikely to join this summer is Declan Rice. The England midfielder has been repeatedly scouted but West Ham are not prepared to do business this year for an asking price considered reasonable either to United or any other suitor at this stage.

Ten Hag’s preferred focus in midfield has always been De Jong but Rice may yet return to the agenda next summer.

Now bottom of the Premier League table, Ten Hag may glance across the city at his former Bayern colleague and mentor Pep Guardiola with a sense of envy.

Guardiola’s Manchester City team are top of the league, having scored six goals and conceded none to begin their bid to win a third straight Premier League title and fifth in six years under him. His Sunday, fresh from a 4-0 Saturday stroll past promoted Bournemouth, was so relaxed he could afford to spend his lunchtime in the city’s Catalan restaurant Tast, in which he is an investor.

For Ten Hag, such serenity must feel a lifetime away.

(Other contributors: Pol Ballus, Laurie Whitwell and Jay Harris)

(Top photos: Getty Images)