Harlequins are at the centre of a Heineken Cup investigation following their quarter-final clash against Leinster last weekend.
Tournament chiefs are to look into circumstances surrounding the second-half blood substitution of Quins replacement Tom Williams and fly-half Nick Evans’ resulting return to the playing field.
New Zealander Evans limped off in the 47th minute, before his replacement Chris Malone was then helped off hurt.
Evans though, reappeared after Williams departed late in the game, with television footage appearing to show Williams winking as he left.
Evans, Harlequins’ principal kicker, rifled a late drop-goal attempt wide as Quins bowed out of Europe, beaten 6-5 at the Twickenham Stoop.