The Blues have the chance to put a further statement down in their quest to win the Premier League title against Louis van Gaal's side, and the Portuguese has revealed that his men have no fear going into the match.
He told reporters: "Old Trafford is a big stadium, 75,000, the bigger the better. When you are trying to win the championship every stadium, every opponent, every game is about three points but it's a place to enjoy.
"I went there at Soccer Aid and enjoyed it. The stadium was full and even the players who were not footballers – the actors, singers, comedians – they were feeling the atmosphere in the stadium and enjoyed it so much that I enjoyed it too, and that was just a charity game."
Mourinho also revealed that he enjoys the big occasions, and joked that he would repeat his feat of Soccer Aid when he came onto the pitch to tackle Olly Murs, if he were allowed to against United.
"It's a place you have to enjoy. Did you see the tackle I made? If I could do it on Sunday, I would. And it's the same referee, Phil Dowd. So if I see [Angel] Di Maria in front of me, dribbling, boom!" he said.
Mourinho's side are top of the Premier League ahead of their clash with United on Sunday.