Bayern Munich thump Barcelona 4-0 in Champions League Bayern's Thomas Mueller reacts after scoring the fourth goal during the UEFA Champions League first leg semi-final against Barcelona in Munich. Picture: Odd Andersen Source: AFP THOMAS Mueller scored two goals as Bayern Munich dominated Barcelona to take a commanding 4-0 lead after the first leg of their highly anticipated Champions League semi-final. Mueller scored in the first half and added another after Mario Gomez and Arjen Robben had also scored in the second half. It was Barcelona's biggest loss in the Champions League since 1997, and a humbling defeat for the team that have been widely regarded as the best in the world for the past few years. While Barcelona turned around a 2-0 deficit against AC Milan with a 4-0 win at home, this Bayern team look highly unlikely to allow a similar comeback in the second leg next week in Spain. Bayern's Arjen Roben celebrates after scoring their third goal during the Champions League semi-final first leg win over Barcelona in Munich. Pictrure: Matthias Schrader Source: AP "We knew we were able to give them a good competition," Robben said. This team has dominated Europe over the last five years and if you beat them like this, I think you can be proud. Lionel Messi started for Barcelona despite injury worries but looked far from his best and was hardly a factor in the match. Barcelona had few chances, while Bayern used their size to outmuscle the Spanish side on set pieces. Mueller headed in from close range in the 25th and added the second in the 82nd. Gomez netted in the 49th and Robben in the 73rd. Bayern Munich's midfielder Thomas Mueller scores in the UEFA Champions League semi-final against Barcelona in Munich. Bayern Munich won the match 4-0. Bayern showed their attacking intent from the start and took less than two minutes to produce the first opportunity of the match when Javi Martinez sent a back-heel pass to Robben, but the winger's shot was saved by goalkeeper Victor Valdes. The German champions had calls for a penalty declined in the 15th when the ball appeared to hit Gerard Pique's arm after a corner from Robben. But Bayern scored after another corner, from Franck Ribery. The ball rolled to the far post, here Robben crossed to Dante. The defender headed back across the goal and Mueller raced to head it in. Valdes got his hands on it but could not prevent the ball from sliding into the net. Barcelona kept possession more than Bayern but was unable to break through its crowded defence until the 29th, when Dante was just a step ahead of Messi to clear a cross from Pedro Rodriguez. Barcelona forward Lionel Messi walks off the pitch after the Champions League semi-final first leg loss to Bayern Munich in Munich. Bayern won 4-0. Picture: Kerstin Joensson Source: AP Another Bayern corner produced calls for another penalty as the ball seemed to touch Alexis Sanchez's arm when he challenged Dante in the air but the whistle stayed silent. The second Bayern goal also came after a corner, with Mueller at the far post rising over Daniel Alves and heading across the goal for Gomez to knock in from close range, although he might have been slightly offside. Bayern's third came as Robben went around Jordi Alba, who was blocked by Mueller as he tried to chase the Dutchman, who slotted the ball inside the right post. Ribery and David Alaba did the work for Bayern's fourth, with Alaba swinging in a pass for Mueller to knock in from close range.