Benfica's interest in Jese Rodriguez has sparked concerns over Mourinho's attitude towards the academy.
He said: "Our academy players responded very well on occasion last year and they're ready to help when we experience difficulties. We're relaxed about this because it makes us feel we have a 50-man squad.
"We will try to give opportunities throughout the season, just like we did last year. Men like Mateos and Juan Carlos are in the First Division because they lost anonymity thanks to playing with the first team last year. Others are fit to help and stay in the forseeable future."