The national team boss remains hopeful that the Blaugrana can progress, and fears a defeat could hurt the Euro 2012 winner's morale.
The Blaugrana were beaten 2-0 at San Siro back in February, but the former Real Madrid coach remains hopeful that the team books its ticket for the quarterfinals in Tuesday's return at Camp Nou.
"It will be a very important game for Barcelona and Spain. The result of Barcelona's match could influence the morale of the national team. It would be a bit problematic if Barca lose the tie, because the players will be a bit crestfallen," he told Efe.
"On the other hand, if they turn things around, they will be high on confidence and get a morale boost. It will be a tough task, but I think Barca can make it happen. It is important that they pull if off and qualify, just like Real Madrid did [against Manchester United]. They make up a big part of the national team and we need players in good spirit."
Spain hosts Finland on March 22, before traveling to France four days later.