United consolidated their place at the top of the league with another confident outing at Old Trafford as second-half goals from Marcus Rashford and Marouane Fellaini made it three wins from three for Mourinho’s side.
Despite a crowd attendance of 75,021, Mourinho claimed that it was only after Rashford’s opener that Old Trafford came to life.
He said: "I didn't see the first goal. I was speaking with Jesse Lingard because Lingard was going to be the next player to come on.
"I saw the ball in the net and all the guys jumping around. It was the first time I saw the crowd. They were very quiet.
"It was easy to know that was a goal because it was the first time I really understood the stadium was full."
Leicester were content to sit back in Saturday's game but lacked the cutting edge that yielded three goals against Arsenal on the opening day of the season.
And Mourinho was quick to praise his side for their handling of the Foxes.
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"Were Leicester very dangerous against Arsenal? Yes. I watched the match many times. Were they dangerous against us? No. Why? Because of us. So we had a very good and solid performance."
He added: "[Jamie] Vardy is a very dangerous player," he said. "I would say he is one of the most dangerous players in the Premier League. Was he dangerous today? No. Why? Because we played so well to control them.”
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