It is understood that the Portuguese has already been agitated by a failure to properly sit down with executive vice-chairman Ed Woodward on targets, and that there is a general lack of communication on the issue.
That follows on from a summer where Mourinho made his ire at the club failing to sign a top centre-half publicly known, although has been further complicated by a difficult season.
Although the Portuguese has steadied United's campaign and his job is no longer under immediate threat, it is remains a distinct possibility that they could part ways at the end of the season.
Some in the United hierarchy are said to be mindful of that, as well as some of the signings Mourinho has already made.
Fred has been cited as a purchase that reflects a wider problem. Although Mourinho specifically wanted the former Shakhtar Donetsk midfielder - and got him for £52m ahead of Manchester City - the manager is said to be highly unimpressed with his performances so far, and the Brazilian has fallen badly down the pecking order at Old Trafford.
The United manager similarly remains uncertain over Victor Lindelof, and no longer trusts Eric Bailly, a defender he previously talked up as one of the potential best in the world and who was one of his first signings at the club.
As it stands, although Mourinho still wants another centre-half - specifically Inter’s Milan Skriniar - United are not currently making a concerted effort to bring anyone in in January.
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