Sky Sports posted a video of the players training and Pogba can be seen changing his demeanour as soon as he got close to Mourinho.
Reports in the United Kingdom noted that the French midfielder has informed the club's executive vice-chairman Ed Woodward of his plans to join Barcelona after his agent Mino Raiola agreed a deal with Spanish giants after the summer World Cup in Russian Federation. "I am the manager I can make these decisions".
Earlier in the day, Mourinho told Paul Pogba he will not captain United again, but insisted they have not fallen out.
Pogba has widely been criticised for failing to produce consistent performances under Mourinho at Old Trafford, but he was in fine form as he helped France to win the World Cup in Russian Federation this summer. "It was the same person who decided Paul was the second captain".More news: Google celebrates 20 years, walks down memory lane
The latest clash between the two figures comes after Mourinho stated that he had removed Pogba as the "second captain" at the club behind Antonio Valencia.
Having lost two of their opening three Premier League games of the season, Manchester United recovered some form to win three games on the spin.
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".
"That has always been the blueprint here, to go for teams, and I don't think Jose Mourinho does that".
Mino Raiola, Pogba's agent, has himself been working on Pogba's exit from the club for months, negotiating personal terms with Barcelona in the later weeks of the summer transfer window.More news: You Are My Friend First Look Reveals Tom Hanks as Mister Rogers
The 55 year old's decision to strip Pogba of his captaincy before the match on Tuesday night was another example of his negative approach towards his players.
The former Chelsea player has revealed what Mourinho said to him in their conversation.
"We are at home and we should play much better against Wolves". That's Old Trafford. We are here to attack.More news: I'd Prefer To Keep Rosenstein, May Delay Planned Meeting On His Fate