Ralf Rangnick held a one-on-one training session with a Manchester United player only for his instructions to be entirely disregarded, according to reports.
The German, 63, is still battling to mould the squad to his requirements having been appointed interim manager at the end of November.
Although the Red Devils secured a morale-boosting victory over Leeds United on Sunday, results have been mixed on the whole to leave their hopes of Champions League qualification teetering.
Away from the pitch, Rangnick's short tenure has been littered with alleged issues behind the scenes including division in the dressing room and a recent captaincy dispute.
There is also said to be unrest with his coaching methods, as many players feel they are outdated and have therefore adopted an unreceptive stance at the club's Carrington base.
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A fresh report in The Independent claims one unspecified star took this to the extreme after a lengthy individual session with Rangnick.
The former RB Leipzig boss is said to have spent 45 minutes explaining where the player was underperforming and how he could address this.
Rangnick felt the session went well and tried to hammer home some of his instructions before a recent fixture, but the player then entirely neglected these during the match.
While the rebel in question remains unnamed, the report does specify certain players who have proved troublesome in matches or at the training ground.
Playmaker Bruno Fernandes was described by one coach as being 'tactically anarchic', midfielder Paul Pogba fails to live up to Rangnick's demands when out of possession and striker Cristiano Ronaldo does not have the desire to press the opposition.
In contrast, forwards Jadon Sancho and Anthony Elanga are believed to have been highly receptive to Rangnick's coaching, and this is viewed as the cause of their recent star showings.
Sancho, 21, is enjoying his best run of form since joining United last summer and contributed two assists against Leeds.
Elanga, 19, was on the scoresheet against the Whites and he has established himself as a regular in the matchday squad.
The duo are believed to be enjoying Rangnick's coaching in the art of the high press, but this is something many other players are very inexperienced in.
Previous manager Ole Gunnar Solskjaer and his predecessors - Jose Mourinho, Louis van Gaal and David Moyes - employed vastly different styles to the one Rangnick advocates.
It remains to be seen whether he can imprint his philosophy in time to bring a consistent run of results with a view to securing a top four finish.
