The former Blaugrana goalkeeper feels that while Massimiliano Allegri's side do not have the household names of old, their history and prestige make them a tough opponent.
"They're a team with a great history who know how to compete in the big games and which are always going to make things difficult for you,” he told reporters.
“[Milan] will always have good players, irrespective of how famous they are. It will certainly be a difficult tie.
“The big clubs know how to compete. They know how to hold out for a result and the pressure doesn't get to them. Milan, Barca, the greats – they know when they are on the big stage and I'm sure Milan are going to prove that to us.”
The former goalkeeper went on to say that neither side can be classed as favourites ahead of the San Siro clash on Wednesday.
“This is a Champions League tie, with everything that's at stake, and when you're playing against a team like Milan, the idea of being the favourite or not is something which generally doesn't exist in the world of football.
“There are no favourites.”
The former Spain international also vowed that Barca would remain true to their philosophy during the tie.
“It's a style of play – keeping possession and such things. You have to read the game, we are a team which will go all out for victory and attack the opponent's goal. That's our style.”