The Bavarians were beaten 3-0 at the Camp Nou last week, and have it all to do in their second leg clash at the Allianz Arena tomorrow night.
And German international Thomas Muller feels his side are still in the tie despite the gigantic task at hand.
"I am neither very euphoric nor very pessimistic," the 25-year-old told a press conference.
"We need to take our chances. Everyone knows that things were better before. We will have a plan.
"That first leg was a huge disappointment,” he continued. “But since we left Camp Nou we've wanted to make up for it. If we go through, it will be a statement for the world of football. This is the plan and it's not stupid.
"In football, many things are possible. That's why there's still hope and we still believe in ourselves. We can't expect things to go like against Porto. But that's what we need.
"We have to find the right mix of better attacking and more calmness on the ball. The three-man defence was a risk against a three-man attack.
"The coach will prepare us well and the rest is will and support from the fans."
Muller then denied claims the team have lost belief in coach Pep Guardiola after suffering four straight defeats.
"I haven't noticed any difference,” he said. “But of course, right after a decisive defeat the mood is not good.
"We have nothing to lose against Barca and this is how the players and the coach are approaching the match. We will give it a try, it is not over yet. We will give everything until the referee blows his whistle."
Kick-off in Germany is scheduled for 20:45 on Tuesday night.