Germany Captain Michael Ballack says his team are wary of England-slayers Croatia ahead of Thursday's Euro 2008 Group B clash which will guarantee the winner a last eight berth.
The 31-year-old Chelsea midfielder was outstanding in his side's 2-0 opening victory over Poland on Sunday as two goals from Bayern Munich's Lukas Podolski got Germany off to a flying start.
But Croatia beat England twice in their qualifying campaign to deny the English a Euro 2008 berth and Ballack says Germany must raise their game if they want to reach the quarter-finals and beyond.
"We are at 80-85 percent of our full potential, but we have to orientate ourselves towards Thursday's opponents," said Ballack.
"We will have a much different task against Croatia, they also want to be European champions and they beat England twice, which is no easy feat.
"We will know our true level after the game, we can be content with our win against Poland, but we have to raise our game, because we will come across stronger teams in the tournament like Croatia."
Germany coach Joachim Loew has tapered down his squad's training in the build-up to Thursday night's match in Klagenfurt, Austria, to let his team recover, but he will demand the same accomplished performance.
"For two days, the training programme has been reduced to allow the players to rest, but we want the same intensity of performance we showed against Poland," he said.
Loew is expected to make few changes from the side who beat Poland with the biggest question being whether he will play Bastian Schweinsteiger in midfield or continue the success of playing Podolski behind the strikers.