Bayer Leverkusen's director of sport Rudi Voeller on Thursday threatened to ban Michael Ballack's agent Michael Becker from their stadium as an ongoing feud between Becker and the club threatened to spill over.
"He should stop attacking us as a club," fumed Voeller in a press conference ahead of Bayer's German league match against Stuttgart on Saturday.
"He has been shown the yellow card, this is the last time he will attack us in this manner.
"That will never happen again or he will never set foot in the stadium again."
Voeller and Leverkusen's managing director Wolfgang Holzhaeuser met with Becker this week for a clear-the-air meeting after comments were exchanged in the media over Leverkusen's treatment of Ballack.
Becker had said Ballack was being treated like a "pawn" by the club, which led to Voeller's threat.
The 35-year-old's two-year contract expires at the end of the season and after failing to claim a regular place in the team Ballack -- whose attitude has been criticised publicly by Holzhaeuser -- looks set to leave.
Last weekend, Holzhaeuser claimed Ballack's return to the Bundesliga after four years at Chelsea had "failed", forcing Becker to defend his client.
Voeller criticised Holzhaeuser's comments, but said Ballack should speak up if he had a problem with the club.
"He has the obligation to speak for himself and not send his agent out for him," said Voeller.
However, several ex-Germany players, including Mehmet Scholl and Dietmar Hamann, have spoken out about Ballack's treatment at Leverkusen, who will play Barcelona in their Champions League round of 16 first-leg match on February 14.
Becker has said Ballack's options at the end of the season include going to play in China, the Middle East or the United States as the ex-Chelsea star brings down the curtain on his career.
Ballack turned out for Germany for the 98th and last time in March 2010. Since then, national team coach Joachim Loew has informed him he is no longer required.