Jehmann and Subotic investigated after clash
"An analysis of the television images showed that Jens Lehmann intentionally hit Subotic in the forehead with his elbow, whereby Subotic reacted and hit Lehmann in the face with his left elbow," said the German Football Association (DFB).
Lehmann was left with a split lip after incident in Saturday's game, the DFB added in a statement on its website.
Referee Helmut Fleischer said he had not seen the incident and both players escaped punishment during the game, the DFB said.
The pair will be asked to make statements before the disciplinary committee decides whether they will face punishment.
The DFB also said that Borussia had been fined 5,000 euros after their fans threw plastic cups onto the field during a German Cup match at SpVgg Weiden at the start of the month.