Commenting further, Mourinho admitted to being torn over who he wants to progress deep into the tournament - due to wanting his Red Devils stars to have a rest before the new season.
The Brazil squad, now preparing for Sunday's friendly against Austria at Tottenham's Enfield Centre, were quick to congratulate Fred on Tuesday after his move was confirmed.
United need to bolster their squad if they are to renew their challenge against cross-city rivals Manchester City, who they trailed by 19 points in last season's Premier League.
Bill Clinton's lame excuses for bad answers
I messed up and I own that,"saying no one else is to blame for that botched interview, "including that young man aggressively saying I did not apologize".
How will his arrival impact Paul Pogba's future?
"What they have got with Mourinho is very different". Pogba plays with more finesse and is a flashier player, capable of producing magical moments. "They have experience, top players, and the right mentality", Mourinho said.
Fred is renowned as a box-to-box all-action central midfielder.
Should United pursue a move for Lazio's big playmaker Sergej Milinkovic-Savic too, however, then real question marks about Pogba's future could be raised. Let us know in the comments. He was tested positive for the diuretic hydrochlorothiazide in a sample taken during the competition and was disqualified from playing.
He was banned from worldwide football for a year by South America's governing body CONMEBOL, but only missed four months for Shakhtar as FIFA did not extend the ban to cover all confederations until February 2016.