Bayern Munich needs to score three goals in 90 minutes without conceding any to extend their Champions League tie on Tuesday.
But Pep Guardiola knows that chasing goals against Barcelona would leave them vulnerable.
"If we only focus on scoring on Tuesday, we will lose in the same way we did in last year's semi-final decider to Madrid," Guardiola told reporters. "We have to stay calm, play our own game and see what happens."
Bayern lost on Saturday while playing with 10 men after Pepe Reina was sent off.
"Bayern have no wingers left who can attack on the flanks," Guardiola said. "We're reliant on our full-backs to attack down those avenues."