A young Frenchman pretending to be a friend of France midfielder Franck Ribery got into the Bayern Munich dressing room after Wednesday's training before being thrown out.
When Ribery discovered the man in the dressing room, he had him thrown out by security personnel.
Bayern spokesman Markus Hoerwick says the two got into an argument but that no threats were exchanged.
Bayern is trying to determine how the man got past security at the club's training ground. Ribery had been speaking about an upcoming visit by his brother and a cousin and that may have been a factor, according to Hoerwick.
Bayern called the police and is trying to get a restraining order against the man, who was not identified.