Mount was left out of the starting eleven despite being one of the Blues most consistent performers in what has been an up and down season.
But Tuchel was eager to explain his thinking and insisted “there is nothing to worry about” for either player.
“I wanted to take the weight off their shoulders,” he said ahead of the match with Burnley this weekend.
“I wanted to give the responsibility in this special moment to a bit more experienced players and have them on hand. There is nothing to worry about, I like what I see from Mason so far. Such a nice and competitive guy.
“Every game I have seen so far, Mason cares for Chelsea, 100 per cent. This is the best basis for a big development. I am very happy to have him around, I will not stop pushing him and guiding him.
“For Billy, I have a good impression. He is a very strategic guy, very high level of game understanding, good in the first contact, clever positioning.
“We will see if he has the physical level. But he is super quick with his feet.”
Tuchel welcomes the Clarets to the Bridge on Sunday for his second game in charge.
He will be boosted by the news that midfielder N’Golo Kante is set to be fit and available after missing the last five games through injury.