Manchester United's players fear that Jose Mourinho's fierce private and public criticism is damaging confidence and already having a destabilising effect on their season.
The squad have been left shocked not only by Mourinho's public censure of individual players, including Luke Shaw, Henrikh Mkhitaryan and Jesse Lingard, but the personal nature of criticism behind closed doors as the United manager faces an early crisis in his reign.
Sir Alex Ferguson's "hairdryer" treatment became infamous at Old Trafford but Mourinho's rebukes are believed to carry a nastier edge that has not gone down well in the dressing room.
United face League One side Northampton Town at the Sixfields Stadium in the EFL Cup this evening on the back of three successive defeats before champions Leicester City visit Old Trafford in a crucial game on Saturday lunchtime.
United's hierarchy were relaxed about Mourinho's abrasive nature and capacity for controversy when they appointed the Portuguese as manager in May and believe he shares many of Ferguson's characteristics.
But one of Ferguson's golden rules was not to castigate players in the media, and while Mourinho retains the steadfast support of United's power brokers, his persistent public criticism already carries echoes of his final months at Chelsea when he lost the dressing room before being sacked.
Several of United's senior players went to see Louis van Gaal to urge the former manager to lay off Shaw after the Dutchman's frequent public criticism of the England left-back during his first season in charge.
There was concern that Shaw's confidence was being eroded by Van Gaal's behaviour and it remains to be seen whether senior players also seek to confront Mourinho over his public criticism of the defender in the wake of Sunday's 3-1 defeat by Watford, and of Mkhitaryan and Lingard after the defeat by Manchester City a week earlier.
Mourinho criticised Shaw for not being closer to Juan Zuniga before he scored Watford's second goal five minutes from time but it emerged that the 21-year-old, still finding his feet after 10 months out with broken leg, was carrying a groin injury at the time that could now keep him out for up to three weeks.
Wayne Rooney has always been a vocal force in the dressing room but the United captain is understood to feel under immense pressure after a disappointing start to the season and is worried about his place in the team against Leicester after a dismal showing at Watford, when he came in for severe criticism on social media from fans.
Mourinho could not stand accused of failing to give Rooney an opportunity if he now opts to drop the England forward but his captain's deployment in a midfield role against Watford contrasted starkly with the manager's insistence in July that the player would "never be a No 6 or No 8" under him.
Mourinho believes he has taken on a bigger job than he initially thought at United as he attempts to effectively "reprogramme" players indoctrinated over the past two years by Van Gaal's risk-averse tactics.
But while United's squad are thought to acknowledge the scale of the task, they are increasingly concerned that process is being aggravated, not smoothed, by Mourinho's tongue lashings.
Most have been taken aback by the sudden criticism given how Mourinho was described by prominent figures at the club as having a "hypnotic" presence over the players, who "stood a little taller" in his company during his first couple of months at the helm.
Mourinho's criticism of Shaw was a surprise given that he recognised early on that his full-backs were among those players who faced the biggest demands adjusting to his methods. Whereas Mourinho wants his full-backs to get forward and overlap, Shaw and Antonio Valencia were instructed under Van Gaal to look primarily to pass inside to the centre-halves.
Shaw and Valencia are not alone. Spanish midfielder Ander Herrera, for example, is being asked to pass and move in a way very different to what Van Gaal wanted and Mourinho is thought to have been sympathetic to the confusion that has occasionally caused in training.
Yet there has been a distinct change of mood since the 2-1 defeat by City, after which Mourinho rebuked Lingard and Mkhitaryan, whom he felt were overwhelmed by the occasion, and in the subsequent losses against Feyenoord and Watford.
The public remarks aside, the private criticism has also been savage.
"His delivery of criticism is nasty," one source said. "It is far more personal than Fergie ever was." Mourinho was accused yesterday of "losing the plot" by Christophe
Dugarry, the former Barcelona striker and World Cup winner with France. "I get the feeling Mourinho's last tactical success was that Champions League [semi-final] game between Inter Milan and Barcelona [in 2010]," said Dugarry, who hosts a radio show in France. "He's won titles since but I think he has lost the plot. He believes he has become more important than the team.
"Tactically, I think he doesn't put anything in place. Apart from the players, who have changed, it's the same organisation as last season under Van Gaal."
There has certainly been surprise in some quarters of the dressing room that Michael Carrick has been overlooked in midfield.
Aside from 61 minutes in the Community Shield win over Leicester, Carrick has not featured at all when former players, such as Paul Scholes, believe the 35-year-old, or Morgan Schneiderlin or the exiled Bastian Schweinsteiger, could offer the sort of controlling presence in midfield that would enable pounds 89?million signing Paul Pogba to flourish.
Carrick may finally get another run out against Northampton
tonight but Mourinho's failure to settle on a system that maximises Pogba's abilities has raised eyebrows with the France midfielder's deployment predominantly in a midfield pairing with Marouane Fellaini yet to convince.