Liverpool are battling to stay in the Carabao Cup.
In ordinary circumstances expulsion from the competition is the standard sanction for using a player who isn't eligible, but Liverpool are understood to be pinning the blame on the FA in the hope of being given a lesser punishment.
Liverpool contend they applied for an international transfer certificate for Pedro Chirivella when he returned to Anfield from a loan spell in Spain with Extremadura last summer, but the 22-year-old had not received clearance when he came off the bench for the final 27 minutes of Liverpool's third-round victory on Wednesday.
The club are blaming the FA for the administrative oversight as they first sought clearance for Chirivella in July, which they will use in mitigation to try to prevent being thrown out of the competition.
The FA's position is that it is the responsibility of the clubs to make sure all their players are eligible to play.