London Welsh's position in England's top-flight Premiership rugby competition is at risk after the club revealed it has been charged with fielding an ineligible New Zealand player in games this season.
England's governing Rugby Football Union (RFU) has announced a disciplinary hearing will take place in London on March 5, with the case centred on the registration of halfback Tyson Keats.
The 31-year-old New Zealander joined the Exiles from now-defunct Italian club Aironi, with the Christchurch-born player having previously appeared for the Crusaders and Hurricanes.
Keats started last Saturday's Premiership game against Exeter and has been an important part of Welsh's debut top-flight campaign.
But on Tuesday the club announced they were facing disciplinary action, having brought the matter to the RFU's attention following an internal inquiry earlier this month.
London Welsh are currently three points above basement club Sale with six league games remaining.
Only the side at the bottom of the 12-team table come the end of the regular season will be relegated and London Welsh are now facing the prospect of a points deduction that could demote them even if they were to otherwise finish above Sale in the standings.
London Welsh added their former rugby manager, Mike Scott, was now the subject of a separate RFU disciplinary hearing relating to Keats's registration and has been charged by the RFU with "conduct prejudicial to the interests of the union or the game''. Scott's case will be heard at a later date.
The Exiles' added "no fault in this matter resides with the player (Keats)''.