Philipp Lahm has undergone surgery on his elbow and faces a race against time to be fit for the World Cup finals.
The Bayern Munich defender damaged his arm on Tuesday when falling awkwardly during a practice game for Germany.
He was taken to hospital and although nothing is broken, Lahm has torn tendons which need repairing.
Lahm had surgery on Wednesday and although the German camp claim it was a success, it is not clear if he will join the squad for a training camp in Geneva.
Germany boss Jurgen Klinsmann will give Lahm every chance to prove his fitness, as he has until June 8 to name a replacement.
"He will be able to resume running in three days and full training in 14 days," Germany's assistant coach Joachim Loew said.
"We assume he will be at the World Cup. There are no plans at the moment to call up a replacement."
Klinsmann's men kick off their World Cup campaign against Costa Rica in Munich on June 9.