"It's a light sprain in the left foot and no one is nervous about it," a spokesman for the German Football Association said.

Ballack, who will lead out the hosts in the opening match of the World Cup on June 9, suffered the injury early in a practice match against Servette Geneva's under-18 team.

Germany play Luxembourg in a friendly in Freiburg on Saturday. It was not immediately clear whether Ballack would be able to play.

The hosts take on Japan [Images] and Colombia before playing the first match of the World Cup against Costa Rica in Munich on June 9.