Jose Paolo Guerrero is in hot water at Hamburg after the Bundesliga outfit confirmed they are to take disciplinary action against the player after he threw a bottle into a fan's face following Sunday's draw with Hannover.
The Peruvian took exception to the spectator's criticism as he was leaving the field at the end of a frustrating match for the northern Germany side and threw the bottle from which he was drinking straight into the fan's face near the entrance to the tunnel.
He will now have to face up to the consequences which, in addition to a potential ban from the German Football Association, will also result in internal disciplinary action.
"I don't care what kind of words were used (to provoke him), that is totally unacceptable," said the club's chairman Bernd Hoffmann on Sky television.
"He will pay the relevant consequences. This does not belong in football."
Team mate Frank Rost tried to play down the incident, although he admitted it was an error to retaliate to the fans who were venting their anger at another lacklustre display from Hamburg.
"It was an error, but he did not do it without a reason," he said. "He hit him perfectly - the New York Yankees would sign him up immediately."
The result left Hamburg in sixth position, four points behind the top five and a guaranteed place in Europe next season.
However, with Stuttgart, Wolfsburg and Frankfurt all winning this weekend, Hamburg now face stiff competition for a place in Europe over the final five games of the season.