England duo Joe Marler and Owen Farrell have both received citings following the weekend's European semifinals.
Marler, who was recently suspended for two weeks for verbal abuse, will face a foul play charge following Harlequins' European Challenge Cup win over Grenoble. Marler is alleged to have kicked Arnaud Heguy.
For Farrell, his charge relates to the tackle on Wasps No.9 Dan Robson in Saturday's Champions Cup semifinal which saw him sin-binned.
Wasps prop Simon Macintyre is also in the dock for allegedly kicking Saracens' Maro Itoje in the same game. Macintyre was sin-binned for the incident during the match while Itoje has been issued with a citing commisioner's warning which equates to a retrospective yellow card.
If Marler is found guilty, he could face a suspension of anything between four and 52 weeks depending on how severe the incident is deemed.
His Harlequins coach Conor O'Shea, speaking soon after their win over Grenoble, defended the loose-head over the incident.
"It was not a boot, it was nowhere near a boot -- it was a shin," said O'Shea. "Any test for a citing has to pass the red-card test. Should he do it? No. Is it a red card? No.
"It's disappointing to have to talk about it because I thought his scrummaging was excellent. But he is under the microscope.
"Things happen, we never condone it but if that is a red card there's a heck of a lot of things that happen on the pitch that are worse.
"So I'd focus on the positives, I'll have a word with him, but there are things happen on the ground. He got up, he did something, but it wasn't a red card."