Pogba took little time to get going at Old Trafford, sending in the ball for Anthony Martial's equaliser and then scoring a third later in the match as Man United recovered from a goal down.
Mourinho - who revealed he allowed Pogba to decide how many minutes he played - feels the presence of the 24-year-old made a telling difference to the way the team performed, particularly in attack.
He added: "Last season we played Zlatan every minute nearly until he was injured but this season we learned how to play without him but he's still a very important player for us and of course we welcome him back". We were saying all along that he will back in 2017 but being back on December 31 is one thing but to be back in mid-November is another. His every touch was hailed by the crowd and he so almost marked the occasion with a goal, Elliot keeping out an acrobatic volley that demonstrated how the Swede has lost none of his flair for the dramatic during his lengthy absence. "Clearly you can see there was a Manchester United this season before and after his injury", added Mourinho.
"Last season we played with Zlatan every minute".
Newcastle counterpart Rafael Benitez felt conceding a second goal just before the break was crucial to his side's chances of getting anything from the game.
"It's simple and clear - when you spend so much money on players of this quality, it is to make a difference in games".
Manchester United could head into their clash against Newcastle trailing league leaders Manchester City by 11 points.
"We know our strengths and weaknesses".