Bayern Munich dominates Spanish side, 4-0, in first leg of the semifinals

Barcelona's assistant coach Jordi Roura has admitted his side needs a miracle at the Nou Camp in the return leg after being hammered 4-0 at Bayern Munich in the Champions League semifinal first leg.

Bayern is on the verge of its third Champions League final in four years after goals by attacking midfielder Thomas Mueller, striker Mario Gomez and Dutch wing Arjen Robben floored Barca at Munich's Allianz Arena on Tuesday.

It was the Spanish giant's worst Champions League defeat since a 1997 group stage 4-0 loss to Dynamo Kiev.

Barcelona's Argentinian superstar Lionel Messi started, despite struggling with a hamstring injury since the start of the month, but the world player of the year was a shadow of his usual self.

"They demonstrated they are stronger than us, they beat us in all departments," said Messi.

"I couldn't do much to alter the result, which was a shame.

"It will be hard at the Nou Camp, but we have to go for it."

Roura, though, accepted his side faced a task which could prove even beyond it.

"Miracles are always hard to make real, 4-0 is a huge deficit to make up," he said. "I don't know if anyone has come back from a score like that in the history of the Champions League, but we'll do what we can.

"This is a big defeat which hurts us a lot."

There were furious protests from the visitors when referee Robert Kispal failed to spot Mueller's body-check on Jordi Alba as Robben scored Bayern's third goal on 73 minutes, but defender Gerard Pique said Barca was well beaten.

"They thrashed us," said the centerback.

"The referee didn't have an influence.

"It is almost impossible for us, but we have to show some face in the return leg.

"They were quicker, stronger and better."

Bayern, which is bidding to become the first German team to win the treble of European, league and cup titles, was buoyant after finding itself on the verge of the Wembley final on May 25.

"That's crazy, hard to believe," said Robben.

"They've dominated Europe in the last few years and and then we go and win 4-0.

"The key was we fought and defended together."

But Bayern coach Jupp Heynckes warned the job is only half done.

"Of course, we're all very happy about the win, especially the size of the margin. We were first class," he said.

"But we know we still have 90 minutes ahead of us in Spain.

"We want to enjoy tonight, but nothing more."

An exceptional day for Bayern got off to an unusual start when it was announced it had signed young German star Mario Goetze from arch-rival Borussia Dortmund for a reported 37 million euros ($48.1 million).

Then it was reported that in March club president Uli Hoeness, caught up in a tax evasion scandal, was arrested and released on bail after a police raid on his home.