Mourinho told Sky Sports: "They are not the last wonder of the world, like you like to say they are, but they are very good team.
"It was more difficult for them than it was for us. We kept control of the game for long periods. In the first half, we were completely in control. In the second half, David De Gea made two great saves but it was out of context.
"We controlled very well the emotion of the game and ourselves and also we could influence the atmosphere of the stadium. They were always showing their disappointment. I thought they were waiting for an easy match for them but it wasn't."
"We had a big chance that I thought Zlatan was going to score. If he did, 1-0, goodbye, it's finished," Mourinho said.
"We missed a little bit of sharpness through the middle, where Pogba was. I expected a bit more penetration."
United were limited to just 35 percent possession - their lowest total since Opta began recording that data in the 2003-04 season.
But Mourinho insisted that figure was not important, saying: "That was the game we played. We knew they wanted to press our first phase of building up."