Saracens’ Champions Cup quarter-final place is in doubt because prop Titi Lamositele may have been ineligible when he played in January’s Champions Cup win against Racing 92.
The defending champions are subject to a misconduct complaint after tournament organisers were informed by the club that United States international Lamositele’s work permit expired the day before the match.
Saracens beat Racing 92 to reach the quarter-finals less than 24 hours after being relegated from the Premiership.
An independent disciplinary committee will hold a hearing at 18:00 GMT on Friday.
French club Grenoble were deducted four points for fielding an ineligible player against London Welsh in the 2012-13 Challenge Cup.
Grenoble had won the fixture 20-9 but London Welsh were awarded a 28-0 victory after the hosts played Lotu Taukeiaho, who was not registered as a tournament squad member.
Though Saracens’ infraction is different to Grenoble’s, a similar change in result would move Sarries out of the eighth quarter-final qualification spot, making way for Glasgow Warriors to reach the knockout stages.
A European Professional Club Rugby (EPCR) statement said that Lamositele may have been ineligible when he came on as a replacement in the 60th minute “due to an inadvertent administrative error on behalf of the club”.
The 24-year-old was eligible when Saracens’ matchday squad was announced, but his work permit had expired before the game on 19 January.
Three-time European champions Sarries had been relegated from the Premiership the day before the match following persistent salary cap breaches.
As things stand, Saracens will play their Champions Cup quarter-final against Leinster in Ireland on 4 April.