Under-21 Republic of Ireland v Georgia: The Republic of Ireland Under-21s are facing a rap on the knuckles from UEFA after fielding an ineligible player in Friday's 2-1 win over Albania.
Celtic midfielder Liam Miller, the under-21 skipper, should not have played, having received two yellow cards during the European Championship qualifying campaign.
However, the two cautions were not spotted and Miller led the side to victory.
The Irish now face punishment from Europe's governing body, which could see the under-21s being stripped of the points gained last week.
The team's manager Don Givens said: "It has been brought to our attention by UEFA that one of our squad members, Liam Miller, was ineligible to play against Albania after picking up two yellow cards in the previous fixtures.
"The FAI has this morning written to UEFA acknowledging and apologising for the error and we have indicated to UEFA that under no circumstances would we play a squad member knowingly aware of a two yellow card situation and this case is a result of (bad) communication and human error.
"We are now awaiting a decision from UEFA but Liam Miller will take no part in the game against Georgia tomorrow and we wait to hear what decision will be made with regards to any further development."
Following the error, the FAI's newly-appointed CEO Fran Rooney has asked for a full report into the incident and the association will introduce a new checking procedure to include a database for all their squads, to ensure the mistake is not repeated. The FAI has also given a commitment to UEFA that it will not happen again.
Miller was booked in the game at home to Switzerland last October and again in the fixture away to Albania in April. In normal circumstances, UEFA send a fax to the FAI and follow that up with written communication documenting a player's eligibility to play, and Givens is now trying to find out what went wrong.
"This has been missed by everyone and we are just checking the facts at the moment," he said.
"There has been an error along the line somewhere and I don't know if the fax from UEFA came into our international department.
"His first booking was eight months ago and I don't think UEFA have got it wrong but we have only just found out so we are still checking.
"We have to think about a team without Liam tomorrow night and also make sure this never happens again."
Apart from Miller, there are likely to be two other changes to the team to face Georgia. Goalkeeper Graham Stack is out with a throat infection so Dan Connor will earn his first cap.
In midfield, Nottingham Forest's Andy Reid is doubtful with a foot injury, and the players competing for his and Miller's place will be Kevin O'Connor, Graham Ward and Keith Gilroy. Nottingham Forest defender John Thompson will captain the side.
Givens added: "The spirit is good in the camp and we're looking for our second successive win. The lads have not trained much since Friday because they were very tired and have been recuperating."
