Toulouse wing Yoann Huget has received a formal warning for feigning injury during his team's European Champions Cup defeat against Bath on Sunday.
European Professional Club Rugby (EPCR) said the warning was issued by match citing commissioner John Charles.
In a statement, EPCR said it followed "an act contrary to good sportsmanship".
France international Huget, 27, was seen to perform a dive in an attempt to gain a penalty for foul play.
He has apologised for the "inappropriate gesture", saying it "did not reflect the values of rugby".
Players who accumulate three citing warnings or three yellow card offences for foul play - or a combination of both - during the Champions Cup and European Challenge Cup competitions will be required to attend a disciplinary hearing.
EPCR also said that Harlequins wing Tom Williams has received a citing commissioner warning for a dangerous tackle on Wasps centre Alapati Leiua during last Saturday's pool game between the clubs at the Twickenham Stoop.