Stuttgart goalkeeper Jens Lehmann may face disciplinary action after an off-the-ball clash with Borussia Dortmund defender Neven Subotic.
The incident occurred just before half-time during Stuttgart's match in Dortmund on Saturday, as Lehmann faced his former club.
Lehmann was jeered each time he touched the ball by the home fans, and two minutes before the interval he wrestled with Subotic inside the penalty area as both players awaited a throw-in.
Elbows were thrown by both players, with Subotic making contact with Lehmann's face, but the referee Helmut Fleischer did not get a clear view of the incident and did not include it in his report.
That enables the German Football Association (DFB) to take retrospective action upon viewing video evidence, which means that both players could be banned.
But Lehmann was incensed as he showed off a split lip after the game.
"In 20 years, nobody has managed to break my jaw or knock a tooth out but it was close this time,'' he said. "If I did something like that, I would be banned for eight weeks.
"I have no idea what they train these people.''
Lehmann fell to the ground after receiving the blow to the face, however he had previously struck Subotic in what he claims was just an "attempt to keep him at a distance''.
Subotic admitted he made contact with Lehmann, but claimed he was reacting to being struck by the former Arsenal goalkeeper.
"Of course I hit Lehmann, but he hit me first,'' Subotic said. "And it's not like I hit him at 250 miles per hour. He did not have to fall over.''
The match ended 1-1, to leave both clubs in mid-table with four points from the first three games of the season.