Professional football players who unilaterally extend their home leave, late-night drinking sprees, a player's criticism of the club's purchasing policy, physical altercations with teammates, or offensive gestures in response to being substituted: Do football clubs have to tolerate such behaviors from their licensed players, or can they impose sanctions on the professionals? The author explores this question in his work, clarifying whether licensed players enjoy the protection of labor law based on the contractual relationships between the club and the player, and what contractual obligations they must fulfill according to the DFL's standard employment contract. This is followed by an overview of the legal instruments available to clubs in cases of breaches of duty by licensed players. Finally, a look is taken at particularly relevant individual cases in practice.