Although the policy established by Sir Alex Ferguson requiring non-playing members of the squad to turn up in official club wear has been relaxed, players are still expected to dress conservatively and this is another area in which staff feel Pogba is setting a bad example.
The Catalan giants have identified Pogba as a future signing, and tension between the Frenchman and United boss Jose Mourinho has only increased the possibility of an exit from Old Trafford.
The Man United boss was livid that Pogba, who was dropped for Tuesday's Carabao Cup game with Championship side Derby, uploaded a photo of him laughing with team-mate Andreas Pereira in the stands.
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The post emerged at 10.28pm, minutes after Frank Lampard's Rams had dumped United out of the cup at the third round on penalties.
Mourinho is under huge pressure at Old Trafford because of United's latest results, and isn't willing to entertain the player's attitude any longer.
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"You are the anti-captain", he said directly to Pogba.
"I think we have more alternatives to show on the field".
It followed comments made by Pogba after last weekend's disappointing home draw against Wolves where he moaned about his side's defensive tactics.
Speaking on Sky Sports he added: "No fallout at all, no problem at all, just a decision that I don't have to explain". The two players remain on good terms but club insiders have noticed they are not as close as before.
Laurent Blanc's name has come up in conversation every time the managerial vacancy has opened up at Old Trafford, and it is really beginning to feel like a matter of when, and not if when it comes to the former French global joining the club.
'When we play like this it's easier for us'.
Lukaku does not want to be seen to be backing Pogba against Mourinho.