BERLIN, Oct. 14 (Xinhua) -- Germany captain Michael Ballack could miss Wednesday's World Cup qualifying game against Wales due to a right calf injury. Ballack missed practice Monday and Tuesday, and team officials said he is questionable for the game in Moenchengladbach.

"He is being treated all the time by our physiotherapists," team manager Oliver Bierhoff said Tuesday. "It's an hour-by-hour process to see how he reacts to treatment. He knows his body the best. We'll just have to wait and see."

Ballack had a similar injury before the European Championship final in June, which Germany lost 1-0 to Spain.

The Chelsea midfielder was hurt during Saturday's 2-1 win over Russia, in which Ballack scored the second goal.

The win put Germany on top of Group 4 with seven points from three games. Wales is second with six.

Germany next plays in Wales on April 1. Wales must beat one of the group favorites, Germany or Russia, to have a chance of qualifying for the 2010 tournament in South Africa. Wales has already lost 2-1 to Russia.

To achieve that goal, Wales has to beat Germany at least once in the next two games