Bayern Munich captain Thomas Muller has said Real Madrid "are vulnerable" ahead of the Champions League semifinal first leg between the teams in Germany on Wednesday.

Having sealed a sixth consecutive Bundesliga title, Bayern are eyeing a second Treble and have lost only two of 36 matches since Jupp Heynckes returned as coach in October.

And Muller said they were confident that they could deny Real a third consecutive Champions League trophy.

"We're aware of Madrid's qualities. We must attack them, must score goals and make use of the weaknesses Real have," he told reporters after Bayern's win at Hannover on Saturday.

"They lost the second leg against Juventus 3-1, and that means that they are also vulnerable. We'll go into this match with a lot of confidence."

Thomas Muller says Bayern are confident ahead of their clash with Real Madrid. Oliver Hardt/Bongarts/Getty Images

Bayern were knocked out of the Champions League by Real in both 2013-2014 and last season, but Poland striker Robert Lewandowski told kicker they could beat them this year.

"It's a Champions League semifinal. If you play with fear, you stand no chance," he said.

"You must be convinced that you can beat Real, don't take it too easy but, in a certain way, remain relaxed.

"It was just a different situation last year. I wasn't fully fit, not at 100 percent, and trudged through it. We were unlucky to crash out.

"I don't care who scores the goal. Our priority is to reach the final."

Winger Arjen Robben, who scored the winner in the 2013 Champions League final against Borussia Dortmund, added: "It wasn't Lewy [struggling with fitness]. We had many problems last year, especially in Madrid.

"We played with a team in which three, four players were at 50 percent. We still fought until the last minute. This year, we are all fit."

Bayern will be without Manuel Neuer, Arturo Vidal and Corentin Tolisso, while left-back David Alaba also faces a race against time after missing the Hannover match with back problems, kicker reported.