Dublin have been dealt a significant blow, after Diarmuid Connolly's one-match ban was upheld by the GAA's Central Hearings Committee (CHC) last night.
Reports had suggested the hearing wouldn't go ahead until this evening but Dublin were in front of the Croke Park committee to make their case last night.
Connolly was seen to strike Lee Keegan after the pair wrestled on the ground late in the game, with referee Joe McQuillan sending Connolly off for his part in the incident while only booking the Mayo man.
Dublin must now decide whether they will take their case to the Central Appeals Committee (CAC), which could be convened before the end of the week.
However, it looks increasingly likely they will now be without one of their most influential players for Saturday's replay with the Connacht champions. Connolly top-scored for Dublin in the drawn game with 1-2, which included converting the Dubs' first half penalty.
The ruling means Connolly is the only player to face any sanction arising from the ill-tempered affair in Croke Park.
Earlier this week the CCCC opted against pursuing any of the other controversial incidents that took place in the game.
Jim Gavin must now look about shuffling his deck for Saturday evening.
Kevin McManamon was the first forward to be sprung from the bench and he could be in line for a start, along with veteran Alan Brogan, who came on with just over a quarter of an hour to play.
Mayo have named an unchanged side for the clash, though changes are expected before they take to the field this weekend. Donal Vaughan is set to start despite picking up a shoulder injury early in the drawn game, while last week's surprise starter David Drake is also retained.
Barry Moran and Andy Moran are held in reserve despite making a significant impact when introduced.
Rob Hennelly holds his place in goal after David Clarke picked up an injury in the quarter-final win over Donegal.
Dublin aren't expected to name their line-up until tomorrow evening.
Mayo (SF v Dublin) - R Hennelly; G Cafferkey, D Vaughan, K Higgins; L Keegan, C Barrett, C Boyle; S O'Shea, T Parsons; D O'Connor, A O'Shea, K McLoughlin; D Drake, C O'Connor, J Doherty.