Two Castres players have been cited following Saturday's contentious Heineken Champions Cup meeting with Munster.
Scrum-half Rory Kockott is alleged to have made contact with the eye of Munster flanker Chris Cloete, while hooker Marc-Antoine Rallier has been charged with making a dangerous tackle on Peter O'Mahony.
Both players will face hearings in Paris tomorrow.
Eddie O'Sullivan said the incidents came as a result of a poor refereeing appointment in Wayne Barnes.
The former Ireland head coach said: "He does not manage games that are fraught and bubbling over.
"He's a very good referee when everything is going smoothly, but he struggles with a game that is bubbling over and right on the edge, and he was out of his comfort zone.
"It was probably a bad appointment. Whoever appointed him should have known that he would struggle in that environment."