Energie Cottbus have suspended defender Igor Mitreski and fined him 10,000 euros for publicly criticising the team.
The Macedonian had complained about the bad atmosphere at the club and criticised those in charge in an interview with Kicker magazine.
He has now been forced to train with the reserves until further notice.
Cottbus coach Bojan Prasnikar told the club's official website: "Every single player has a responsibility for the discipline in the team. Criticism is okay, if it is voiced internally.
"We have to accept each other and be aware of our responsibility for our sporting aims. Whoever behaves like that has to deal with the respective consequences."
Cottbus have won just one game in 11 so far this season and lie bottom of the Bundesliga.
"We are taking these measures despite the injuries to Mario Cvitanovic and Stanislav Angelov which have made our personnel situation fraught, because we can not accept such conduct," added general manager Steffen Heidrich.