Werder Bremen defender Theodor Gebre Selassie will require surgery after breaking a bone in his hand during training on Tuesday.
The Czech Republic international hurt his left hand and has been diagnosed with a broken metacarpal.
"I have a lot of pain," he told the club's website.
Coach Thomas Schaaf added: "We are very sorry for Theo that he has suffered this injury. We hope that he is able to return quickly."