UEFA has opened disciplinary proceedings against Marseille defender Patrice Evra after he appeared to aim a kick at one of his own supporters.
The incident occurred prior to the French side's 1-0 defeat to Vitoria de Guimaraes on Thursday evening as they went through their warm-up routine.
Evra was filmed having a heated exchange with his own set of travelling fans and then seemingly caught one of them in the face with a karate-kick style boot.
UEFA will look into the incident at its next meeting on November 10, while Marseille have also launched an investigation.
"Olympique de Marseille has noted the altercation between an individual and Patrice Evra during the warm-up at the game against Guimaraes," a club statement read.
"An internal investigation has been opened to establish responsibilities. No matter what happens, a professional player must maintain self-control despite provocations and insults, no matter how unjustified they may be."
Evra was shown a red card by the matchday official and has been told by UEFA that he faces a ban of "at least one match".