Werder Bremen have warned Marko Arnautovic that he must improve his attitude or he will be offloaded.
The Austrian striker has only been with the Bundesliga outfit for a month, having completed a summer switch from FC Twente.
However, he has already angered his new employers with an apparent lack of effort in training and in recent pre-season friendlies.
Arnautovic has a history of causing trouble, with a loan spell at Inter Milan last season seeing him clash with coach Jose Mourinho on numerous occasions.
Bremen are now experiencing similar problems and have told the 21-year-old that he will be moved on if he does meet the standards expected of him.
Club director Klaus Allofs told BILD: "We will give Marko a deadline.
"If he does not understand that we can only exist if we work together then he does not have any future with Werder."
Bremen hope the issue will be resolved as quickly as possible, as they are reluctant to part with a player of considerable talent.
Allofs said: "Marko is capable of extraordinary things, but he has got to learn how to fit in.
"He has some catching up to do."