A record crowd of 42,200 flag-waving fans watched a Germany training session open to the public yesterday.

"We didn't expect as much of a frenzy as this," coach Jürgen Klinsmann told reporters as he continued preparing his team for the World Cup opener against Costa Rica in Munich tomorrow week.

"It's fantastic the people are already in World Cup fever. It's a great thing to get support like this. We want to repay it."

The 90-minute session was capped by players throwing and kicking 500 balls into the Dusseldorf crowd.

German Football Association (DFB) officials said the crowd was twice as big as the previous record for a public session, 20,000 in Cologne in November 2005.

"It's an incredible atmosphere and will give us an extra kick," said captain Michael Ballack. "This is truly a once in a lifetime moment."

Germany's final World Cup warm-up match is against Colombia in nearby Munchengladbach tomorrow.

All 32 World Cup teams have to hold at least one public training session ahead of the tournament.

Meanwhile, Klinsmann defended his team's back four after they gave up two goals and a half dozen chances in a 2-2 draw against Japan in a World Cup warm-up match on Tuesday night.

"There will always be mistakes," Klinsmann said after the squad left their training camp in Geneva on Tuesday.

"Our aim is to minimise the number of mistakes and make sure everyone covers for each other. But we'll never completely prevent mistakes from happening. They're a part of football."

Klinsmann's boss at the DFB, Theo Zwanziger, normally an ardent supporter of the coach and his offensive style of play, was surprised at all the chances Japan had.

"We could have given up five or six goals," said Zwanziger, the DFB co-president. "That's got to make us all worried."

But Klinsmann dismissed fears his offensive strategy left the team vulnerable to counter-attacks after the speedy Japanese opened a 2-0 lead midway through the second half that revived memories of Germany's 4-1 defeat against Italy in March.

"We believe we're all one unit," Klinsmann said. "If we lose the ball, then everyone has to go all out to get the ball back as soon as possible. Everyone has to work for each other. We'll discuss the mistakes critically but internally."

He also brushed off criticism that he has used 20 different defensive formations in the last two years and said he would continue testing different line-ups right up to World Cup kick-off.

"We'll use the four defenders that we feel fit a match the best," he said, adding that tomorrow's match against Colombia might not necessarily be the same as a week later.

"We're still testing. You'll all have to wait and see."

Injured left back Philipp Lahm could play against Colombia.

"Philipp is in our planning. We hope he'll be able to play, but we'll have to see whether he is fully ready," Klinsmann added.