Matic was an integral part of Mourinho's Chelsea side which won the Premier League in 2015 and the Portuguese admitted he initially felt as though he had "no chance" of being reunited with the Serb at Old Trafford.
"Nemanja is top player with a top stability and we need that".
Jose Mourinho explains why Man United will hit form after Christmas
The new season is upon Manchester United and Jose Mourinho is about to start his second campaign as the club's manager. Mourinho has won the domestic league title at the end of his second year in each of his five major management jobs.
"The manager told me I have to do my job, Paul has to do his". When you play for Manchester United everybody has a job to do, and obviously mine is to score goals and to keep the ball for the team. They look more balanced as a team, with Matic's huge reach and omnipresence allowing others - Pogba especially - to find pockets of space further forward. "I enjoyed the confidence levels".
Matic was Manchester United's best player in an otherwise disappointing 2-1 loss to La Liga champions Real Madrid in the Uefa Super Cup on Tuesday night.
Sky Sports correspondent Kaveh Solkehol has claimed on his personal Twitter account that the west London club were keen to hold on to the Serbian central midfielder.
Barnaby Joyce tells Parliament he may be NZ citizen
The loss of a Coalition MP in the Lower House to citizenship rules could put the government's one seat majority at risk. He will not step down as deputy prime minister while the High Court considers his eligibility to sit in the parliament.
"When I joined Manchester United past year, I thought immediately that we needed a kind of Matic", he said ahead of Sunday's home match against West Ham.
Football host Jake Humphrey was impressed with Matic's performance, tweeting "what were Chelsea thinking".
Kenya: Hellen Obiri Wins 5000m Gold for Kenya
It marked Felix's 11th world title and 17th medal following 400m bronze earlier in the Championships and 4x100m gold yesterday. Obiri claimed the opening gold medal of the night after a blistering acceleration midway through the final lap of the 5,000m.