Lionel Messi and Barcelona hope to become the first team to advance in the Champions League after losing the first leg of a knockout matchup by four goals.
Bayern Munich routed Barcelona 4-0 last week in Germany, and the teams meet Wednesday night in Spain at Camp Nou for the second leg of their total-goals semifinal.
"We need to go for a comeback," Messi said.
The winner plays Borussia Dortmund or Real Madrid in the final at London's Wembley Stadium on May 25. Dortmund beat Madrid 4-1 in the first leg.
Nursing a hamstring injury, Messi failed to make an impact last week.
"People are talking a lot about a German final at Wembley, but first there is Barcelona," Bayern coach Jupp Heynckes said. "We have to play with the same passion, the same concentration and the same tactical plan."
Bayern has won 17 straight away matches in all competitions. Barcelona has lost once in 26 home games this season and overturning a 2-0 deficit from the first leg against AC Milan in the second round.
Barcelona will likely be without injured defenders Javier Mascherano and Carles Puyol, and left back Jordi Alba is suspended because of yellow card accumulation. Defender Eric Abidal and midfielder Sergio Busquets will miss the match because of injuries.
The last time Bayern played at the Camp Nou, Barcelona won 4-0 in the first leg of the 2009 quarterfinals.