Saracens flanker Mike Rhodes has been cited for an alleged headbutt on Robbie Henshaw during his side's Heineken Champions Cup win against Leinster on Saturday.
The South African is facing a ban after being alleged to have struck Leinster centre with his head in the opening stages of Saracens' 25-17 quarter-final win in Dublin.
A European Professional Club Rugby statement read: "Rhodes is alleged to have committed an act of foul play in that he struck the Leinster centre, Robbie Henshaw (No 12), with his head in the second minute of the match in contravention of Law 9.12.
"An independent disciplinary committee comprising Simon Thomas (Wales), Chair, Frank Hadden (Scotland) and Val Toma (Romania) will hear the case by video conference on Tuesday, September 22."
The complaint was made by the match citing commissioner Beth Dickens.
Under World Rugby's foul play laws, striking with the head carries a sanction of a six-week ban for a low-end offence, 10 weeks for mid-range and from 16 to 104 weeks for a top-end offence.
A suspension would be a setback for Saracens, who are already without suspended talisman out-half Owen Farrell.