The Serbian joined the Red Devils from Premier League rivals Chelsea previous year and has quickly established himself as one of the key midfielders in Mourinho's squad.
But Matic, who also played under Mourinho at Chelsea, has revealed why he thinks the Portuguese manager is hard to work with.
"The manager said to us we have to try to shoot and to give some crosses towards him because he is young and it is his first game", Nemanja Matic said.
"I knew how good the goalkeeper was, I told the players that".
"Phil Jones was on the bench because he felt that if we really needed him, he could [play]", the manager said.
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But with a rock-solid rearguard he also knows United will usually be in with a chance of winning those games.
"This is football and I know he is a great goalkeeper and I wish him well for the future".
"Sometimes, I feel being good defensively is a crime, but that is a way of getting results". The Terriers were the first team to win three consecutive league titles in England, but Liverpool, Manchester United and Arsenal have since matched the feat.
However, former United midfielders Roy Keane and Paul Scholes, speaking as TV pundits for ITV and BT Sport respectively, have backed Mourinho.
The Yorkshire club hasn't won any of the last five Premier League matches where they've drawn in two while losing the remaining three.
Next up, the Red Devils will collide against Huddersfield Town on Saturday.
"But, again, you know, 12 matches, 10 victories, two draws, nine clean sheets".