Cian Healy could be facing a three week ban after he was cited for an act of foul play in Leinster's 24-9 defeat to Toulon at the Stade Felix Mayol.
The Leinster prop was sinbinned by ref Nigel Owen in the 26th minute after appearing to use his knee to strike opposition hooker Guilhem Guirado at the fringes of a ruck.
Healy will appear before a disciplinary hearing in Paris on Thursday ahead of the visit of the four-in-a-row chasing champions to the Aviva Stadium on Saturday.
World Rugby's sanctions for foul play, law 10.4 (a), 'Striking with the knee', range from a minimum of 3 weeks to the top end sanction of 52 weeks.
Meanwhile, the Blues have de-registered injured flanker Jack Conan and added scrum-half Nick McCarthy to their Champions Cup squad.
