The respective futures of both Mourinho and Pogba are increasingly dividing the United fan base and their relationship has been described as 'broken' after the manager's decision to strip the Frenchman of his role as vice captain.
Pogba was rested for Tuesday night's Carabao Cup defeat at the hands of Derby County and watched the game from the stands at Old Trafford alongside Luke Shaw and Andreas Pereira.
But rather than keep his head down mere hours of the shocking revelation about losing the armband, Pogba filmed a video of himself joking around with his teammates during the game and posted it on Instagram.
That further irked many United fans already growing tired of his antics and it may well have been the reason that Mourinho had a thing or two to say as the squad arrived on the training pitch at Carrington the morning after.
Pogba initially seemed in a vibrant mood as he ran over to greet Michael Carrick and another coach, But after what looked like a word of warning from the boss, the World Cup winner looked somewhat bemused and appeared to argue his case in the clip captured by Sky Sports.
Speculation is rife that Pogba has informed the club he wants to leave, with Barcelona tipped to make their move in January. United are said to want a £200m world record fee.