Mourinho's summer signed made his debut for the club in their 0-3 Champions League victory away in Switzerland against Young Boys last night.
The Manchester United manager was impressed with his new signing and believes that he can be at the club "for the next ten years".
"It [Dalot performance] was a very good, solid performance after knee surgery. Everyone can see the potential and everyone could see he's a 19-year-old player who has more than 10 years to play for Manchester United," Mourinho told 'Sky Sports'.
"I want to be also nice to Luke [Shaw], because both played at the same level. They played very well. Our danger came from both. They had fantastic movement, they had depth, they had crosses, assists and were involved in the most dangerous actions. They defended well, too.
September 19, 2018
"We knew we had to win this match, we knew it was very important for us to go into the next three matches with Valencia and Juventus twice with these three points and we did that.