Augsburg have confirmed defender Jeffrey Gouweleeuw has undergone a successful operation to repair a collapsed lung.
Gouweleeuw had complained of breathing problems and was examined by the team doctor and pulmonary specialists, the club said in a statement.
Augsburg expect the 25-year-old, who has played every minute of their season, to be unavailable until early 2017.
"The Dutchman suffered a spontaneous pneumothorax (collapse of the lung) and already went under the knife on Thursday," the club said. "According to the doctor, the operation was successful.
"The 25-year-old will almost certainly not be available for [head coach] Dirk Schuster, before the winter break. Gouweleeuw's exact time out on the sidelines depends on how the healing process runs."
Sporting director Stefan Reuter admitted the loss of Gouweleeuw comes as a big blow to Augsburg, who are already without Jan-Ingwer Callsen-Bracker, Marvin Friedrich, Caiuby, Dominik Kohr and Raul Bobadilla.
"This is a bitter injury both for Jeffrey and the team, particularly as our list of long-term injuries has now increased," he said.
"However, Jeffrey's health counts the most. We are confident that he will be able to overcome this injury."