Glen have until Wednesday afternoon to decide whether to lodge an objection following their defeat in Sunday's All-Ireland Club Football Final.
They were beaten 1-11 to 1-9 by Kilmacud Crokes at Croke Park in Dublin.
However, during the final stages of play Kilmacud had two extra players on the pitch.
As the picture above shows, 16 players were actively involved in defending against Glen. Dara Mullin was due to go off when Conor Casey came on, but both remained on the pitch.
Paul Mannion was also still technically on the pitch, albeit closer to the sideline.
In a statement Glen said: "Our chairperson Barry Slowey confirmed we would seek clarification from the GAA on the breach of rules at yesterday's AI SFC club final."
WHAT HAPPENED NEXT?
The GAA told Glen they would not investigate the matter without an official objection being lodged by the club.
Glen said it was "extremely disappointing" to be put in that position and would take time to consider next steps.
WHAT HAVE THE GAA SAID?
In a statement the GAA told UTV it was for Glen to lodge an objection to the outcome of the game "in accordance with Riail 6.44, TO 2022".
"Should they decide to do so, the C.C.C.C will consider the matter. As of yet they have not lodged an objection to the game (they have three days from the starting time of the game to do so)."
That means Glen have until 3.30pm on Wednesday to lodge an objection.
WHAT HAS BEEN THE REACTION?
Former players have criticised the GAA for putting the onus on Glen to appeal the decision.
Former Derry star Joe Brolly took to social media, saying the GAA should be investigating how it happened and should have already ordered a replay.
"Otherwise there is no integrity in our system," he tweeted. "The GAA’s reputation will be zero. This has nothing to do with Glen or Kilmacud."
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