Barca need to bounce back after defeat at AS Monaco and also to Osasuna in LaLiga on Saturday.
Casado spoke to the press at Monday's UEFA media conference.
Step up from Barca Atletic:
"The difference is noticeable, moving up so many categories is noticeable: physically and because of the quality of the rival. But the team helps the youngsters, it gives us confidence. It's easy to play with world-class players like Pedri, Raphinha..."
Message from coach Hansi Flick:
"I think he is a friendly coach, he gives us confidence and has us focused. After the defeat at El Sadar, the team wants to turn things around. We have to play at 100% to win. We have to offer our best version to give the fans a victory."
Defeat in Pamplona:
"I think the team is ambitious to win the first Champions League match. Nobody likes to lose, but we have a good mentality and we hope to win."
Your status?
"I think we have a very good squad, although it is young. Many of us started in professional football, but we all have the ambition to win titles and matches. This club and this badge deserve to give their all and play to win as many titles as possible."
More on Flick:
"He's helped me start playing, he gives me confidence to play and he tells me very clearly what I have to do. He's helped me a lot to give my best and get 100% out of every training session and every match."
Facing Young Boys:
"We know it will be a compact team, we have to watch out for the forwards. We have to watch out for counterattacks, that's where they can hurt us."
Frenkie de Jong's return:
"His return will be good news for us, the more we are, the better. The manager hasn't told me anything. I hope Frenkie plays as soon as possible."
Your form?
"I'm feeling comfortable, good. Everyone is helping me a lot, I'm happy."
Tactical work with Flick:
"I think that the coach and I have things very clear. We analyse the opponent and the post-match. Things are going well, we all understand each other."