Bayern Munich took a giant stride towards avenging their defeat in last year's Champions League final on penalties after inflicting upon Barcelona their worst defeat in Europe for 16 years in the semi-final first-leg at the Allianz Arena.

Thomas Muller helped Bayern put one foot in their third final in four years, opening the scoring mid-way through the first half after Dante's header across goal, before the German's own headed cross allowed Mario Gomez to volley home to double the lead despite being in an offside position.

Arjen Robben added a third in controversial circumstances after Muller blocked the run of Barcelona's Jordi Alba but when the 23 year old snatched a fourth with 10 minutes left, Barcelona, seeking to reach a third final at Wembley, could have few complaints.

The Catalans, with Lionel Messi far from fully match-fit, toiled throughout in Munich and now require a record-breaking recovery in the second leg at the Camp Nou next week.

The result crowned a superb day all-round for the runaway German champions, who confirmed the signing of Mario Goetze from Borussia Dortmund in the morning of the game, and the result against a Barcelona side once considered the greatest club team of all time will send shockwaves across the continent.

Bayern Munich
Munich took one step towards may's final with an emphatic display.

"We've been playing extraordinary football all season," claimed manager Jupp Heynckes.

"It was not a really big surprise to me that we scored four goals. We have played to a high level all season.

"You have got to analyse the other team and I did that," he added "How do they play? What is their style? Where do they move? You have got to have something to hold against that and I did that.

"I had a powerpoint presentation to show the different ways Barcelona work and move. My team was very tactically disciplined.

"My players were fantastic again. Falling short of success in the past two seasons has only made them more hungry for success this year.

Lionel Messi
A far from fit Messi played a peripheral role throughout.

"We defended so well and in possession we have style of play going forward. We have a lot of creativity and a lot of class and quality.

"The fact that we did not concede a goal was very important and the fact we scored four goals was even nicer for us."

With a four-goal deficit to overturn in the first leg, Barca midfielder Xavi, a member of the victorious Champions League side in 2006, 2009 and 2011 says the La Liga champions elect face an "impossible" task to reach May's final.

"It's the worst result ever," said the Spanish international. "They were better - and I don't mind saying that.

"It's almost impossible," he confessed. "But we must try to, for this club and for everyone."