A loophole in Scottish FA rules means Dundee United's Calum Butcher has escaped punishment after an alleged case of mistaken identity on Sunday.
The governing body was keen to punish the 24-year-old for an off-the-ball clash with Celtic's Virgil van Dijk during the Scottish Cup quarter-final.
But its rules prevent it switching punishment retrospectively.
Fellow midfielder Paul Paton was sent off instead by referee Craig Thomson and United have lodged an appeal.
His case and that of defender Van Dijk, who was also shown a red card, will be heard by a judicial panel on Thursday.
But the inaction against Butcher has angered Celtic as it will allow Butcher to play in two upcoming games between the sides.
"It seems completely illogical and fundamentally unfair that, in an incident where mistaken identity has been claimed, the Dundee United player now identified clearly as being involved in the incident appears to have no case to answer - and would be available to play in the League Cup final and the Scottish Cup replay between the two teams - while Celtic's player may potentially miss both of those matches," said a club statement.
"Celtic Football Club and Virgil van Dijk maintain their position that no red card offence was committed by Virgil."
United have refused to comment about Butcher's case.
The SFA has taken retrospective action against United striker Nadir Ciftci, who has been offered a two-match suspension for allegedly kicking Celtic midfielder Scott Brown on the head during the same incident.