Munster and Ireland fly-half Ronan O'Gara has been cited for allegedly kicking an opponent during Sunday's Heineken Cup clash with Edinburgh.
The 35-year-old was reported by citing commissioner Alberto Recaldini after a second-half incident involving Edinburgh lock Sean Cox during the game at Murrayfield, which Munster won 26-17.
If found guilty, O'Gara could find himself banned for some or all of Ireland's RBS 6 Nations campaign, which begins away to Wales on February 13.
The citing, under law 10.4(c), carries a low-end entry point of a four-week ban, with a top-end sanction of anywhere between 12 weeks and a year should he be found guilty.
Racing Metro centre Fabrice Estebanez has also been cited for allegedly striking Saracens and England wing David Strettle with his arm during his side's 37-28 defeat on Saturday.
His charge under law 10.4(a) - striking an opponent with the fist, arm... head or knee - carries a low-end entry point of a two-week ban with a top-end entry point of at least eight weeks.
Stade Francais lock Juan Cruz Guillemain faces a more serious charge under the same law after allegedly striking Grenoble's Fabien Alexandre with his head. The top-end entry point for Guillemain's citing is from 16 weeks to two years.
All three cases will be heard in Dublin on Thursday, with His Honour Judge Jeff Blackett passing judgement on O'Gara while Ireland's independent Judicial Officer Pat Barriscale will rule on both Estebanez and Guillemain.