Mourinho has been criticised for his failure to bring youngsters through at previous clubs, but the likes of Scott McTominay and Demetri Mitchell - both of whom are 20 years old - were among the players to be given a chance towards the end of last season.
The Portuguese expects that duo to lead the next generation of United academy products, insisting that he has no problem with playing youngsters if they are good enough for the first team.
"I think Scott and Demetri are also kids to have a future in the club and Andreas Pereira is back. Probably in a few years Man United will also have half a dozen of these kids [in the team]," he is quoted as saying by The Guardian.
"The reputation is the reputation. But the other day I found myself in the tunnel before the Real Madrid game. I'm not talking about the second half because [those players] were kids who were 15-16 during my time there. But in the first half more than half the Real team, which is their first team because they were only missing [Cristiano] Ronaldo and [Sergio] Ramos, all these guys started with me and had debuts with me.
"They came into the first team with me, they trained with me when they were 15 and 16 years old. Nacho, Casemiro, [Dani] Carvajal, Marcelo was 20. Almost all of them. So when the kids are good and have potential, there is no problem [for me to play them]."
United take on Barcelona in the early hours of Thursday morning looking for a fifth win from five games on their pre-season tour of the United States.