Pep Guardiola has said Bayern Munich will only beat Real Madrid in Wednesday's Champions League semi-final with a vastly improved display after their lacklustre Bundesliga win at bottom-side Eintracht Braunschweig.

European champions Bayern ended a run of three Bundesliga games without victory with an unimpressive 2-0 win at Braunschweig on Saturday, four days before their semi-final, first-leg at Madrid's Bernabeu.

"We won't reach the Champions League final unless we put in a commanding performance against Real Madrid," said Guardiola.

"It's not been easy for us after winning the German title, but we fought despite a difficult situation."

Having beaten Real in a penalty shoot-out in the 2012 Champions League semi-finals, Bayern have been dubbed "la bestia negra" -- black beasts -- by Real fans, but chairman Karl-Heinz Rummenigge said they must prove themselves.

"We have the nickname 'la bestia negra', but now we have to provide some proof of that in Madrid," said Rummenigge, who said he hopes Real's Cristiano Ronaldo will face Bayern.

"When Real Madrid play Bayern Munich, it's a game the whole world will be watching. I'm always for seeing the best players on the pitch."

Peru veteran Claudio Pizarro, 35, and Croatian striker Mario Mandzukic were on target in Braunschweig with late goals in what was only Bayern's third win in their last seven games in all competitions.

Bayern needed 76 minutes to breach the Braunschweig defence with the hosts battling to preserve their top-flight status.

The breakthrough came when Mario Goezte found Pizarro and he scored Bayern's first goal in their last three league games.

With the Braunschweig defence growing tired, Mandzukic grabbed their second three minutes from time as Bayern won their first league match since winning the title nearly four weeks ago with a record seven games to spare.

"I am sure that everyone will put in a top performance on Wednesday, because if they don't we have no chance," said captain Philipp Lahm.

Just as they were in recent consecutive defeats to Augsburg and Borussia Dortmund, Bayern looked lethargic, despite Guardiola's pre-match wish for a polished performance to take a "good feeling" to Madrid.

"The most important thing was that we won before the game against Real Madrid," said Pizarro.

"It has given us confidence and as a striker, it's always good to get a goal, so I am pretty pleased with that."

Bayern can expect a battle royal against Real, who have reached the Champions League semi-finals for the fourth season running, but last reached the final in 2002 when they claimed their ninth European crown.

"It was a good test for us, especially in terms of having to fight for things," said Bayern's Germany star Thomas Mueller.

"We accepted their challenge, kept our patience and fought well, especially in the second-half. That will put us in good step for things to come."

Bayern were without Manchester United-target Toni Kroos and Rafinha, who were both suspended, while left-back David Alaba was missing with a cold.

Germany goalkeeper Manuel Neuer sat out the trip to Braunschweig, but should play in Madrid after recovering from a calf injury.