Mourinho says he only lets loose when a trophy is won.
He told The Sun: "Maybe you can understand why I'm not over the moon because we won at Old Trafford.
"It was, of course, an important win and I know we can go on from here to win the Champions League.
"But I also know we can be out in the next round because the Champions League is full of good teams.
"So I am calm and I am cool."