Sources close to the club were not surprised by the latest development, which will only increase speculation as to whether Pogba will stay at Old Trafford.
The France international captained the side in the Premier League openers against Leicester and Brighton in the absence of Antonio Valencia, just as he did in last week's Champions League win at Young Boys.
Pogba scored two and set up the other in the 3-0 victory in Switzerland, only to under-perform on Saturday's return to league action against Wolves.
The 25-year-old was dispossessed in the move that led to Joao Moutinho's equaliser, with the midfielder saying afterwards that United should "attack, attack, attack".
Those comments are understood have got under Mourinho's skin, while Pogba took umbrage at the way they were reported.
"Some people make polemic even from 'good morning' to create drama," he posted on Twitter. "Big Pogoodmorning everyone hope u get it twisted."
Odds correct as of 1915 BST on 25/09/18