Flick also insists he's happy with the make-up of his squad with two weeks remaining in the summer market.
Flick said, "Valencia plays very well and it is a fantastic challenge for my team to start in LaLiga. We are looking forward to the debut in Valencia. We know that they will look for spaces for us and that they will play with the forward goalkeeper.
"We have 22-23 players registered and tomorrow we will activate the list. Dani Olmo is not ready to play tomorrow, even if his registration arrives. He joined very late. Everyone who plays has to be one hundred percent and in full condition."
On Pedri, Flick said: "He is a special player and I like having him back. It could be an option for the second-half.
"I'm happy with what I have right now. The rest is a mystery. I believe a lot in the club and I have to say that I am very happy with what the team shows and when the injured return we will be very strong."