But, having seen the 25-year-old emerge as such a powerful presence for his country in France, Mourinho believes that can only be positive when he eventually returns to Manchester at the start of next month.
The 29-year-old scored 11 times and provided 9 assists for the Serie A side in the league last season and Mourinho has heaped praise on the player by claiming he is different from other wingers due to his physicality.
"I think that's the point about his performance level and his contribution to a winning team".
After France's victory on Sunday, former United defender Rio Ferdinand said it was "down to Jose to unlock this Pogba we saw at the World Cup because he was responsible, he stood up to a lot of hard tests in midfield, and was a talisman for this team". "I've had a good chat with him and I look forward to the new season and getting back to my best".
United plays its first English Premier League game of the season on August 10 against Leicester at Old Trafford.
He said: "First of all I want to say how proud I am to be a part of the Manchester United family".
The left-back has struggled to establish himself since Mourinho arrived in 2016 and started just eight Premier League games last season.
Nine first-team players will miss the entirety of United's fortnight stay in the States and it won't be until next week that the trio of Nemanja Matic, David De Gea and new signing Fred link up with the squad.
"I'm anxious because I'm not training and then go to the Premier League without lots of players".
Sources said Sanchez is hopeful of clearing up the issue in the coming days and should be free to join Jose Mourinho and the rest of the squad in Los Angeles this week.
Luke Shaw, Andreas Pereira, Antonio Valencia, Anthony Martial as well as Chris Smalling were all on parade during the basic warm-up exercises to loosen muscles after a long flight.
"And I think it's a remarkable move".