"They gave us a thrashing," he said. "We will try to turn it around in the return leg [on May 1] and put in a good performance for the fans.
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"They were better and faster than us. There is no point talking about the referee, there is no excuse."
Arjen Robben, who sparkled on the wing for Bayern and scored one of the goals, hailed his team's spectacular performance.
"We knew we could give them a good game," the Dutch international told ITV. "Before everybody said it was a 50/50 game and we can be very proud.
"Barca have dominated Europe over the last five years and we beat them in such a terrific way. On the other hand let's be quiet... because there is still a second game to play."
There was a suspicion of offside over the second goal by Mario Gomez while Robben's effort was allowed despite a clear barge by two-goal Thomas Muller on Barca defender Jordi Alba.
"I don't want to speak about this, I want to speak about the way we played tonight," said Robben. "We can be proud, everybody played a perfect game, we fought for every metre and we didn't give them any space to play.
"I think maybe they had one chance, maybe two good opportunities but not more and I think in the end we really deserved to win."
For Barcelona, winners of the trophy in 2009 and 2011, it was their joint heaviest ever defeat in European competition.
