Celtic's appeal over the red card shown to Auston Trusty in the draw at Hearts has been dismissed, following a Scottish FA hearing.
The defender was initially booked by referee Steven McLean for his tackle on Pierre Landry Kabore, who tried to get on the end of a through ball.
However, the VAR (video assistant referee) advised an on-field review and McLean then decided Trusty had denied Hearts a goalscoring opportunity, and the player was sent off.
League leaders Hearts took full advantage late on as they equalised through Claudio Braga .
Celtic after that draw, six points behind Hearts and two adrift of Rangers, who are now second.
Trusty will now miss Celtic's next league match, at home to Falkirk on Sunday.
In a statement, Celtic said they are "very disappointed" at the result of the appeal.
They added that "it is difficult to see how the original yellow card decision is a clear and obvious error" and insist they will "be ensuring further discussions with the SFA on the matter" after receiving the written judgement, as they "seek to understand the rationale for this and other decisions".
Manager Martin O'Neill expressed his disappointment after the appeal was dismissed.
Speaking ahead of the Europa League clash with Utrecht at Parkhead on Thursday night, O'Neill, in his second spell as interim boss this season following his time as permanent boss between 2000 and 2005, said: "I'm just disappointed, really.
"I thought the referee's decision in the first place was a yellow card, I didn't think it was clear and obvious.
"But it was nice to get backing from a lot of referees who have refereed a lot of big, big matches when they were interviewed (in media) afterwards, but anyway, it is what it is."
Quizzed about Celtic's statement, the Northern Irishman added: "I didn't know about that, sorry. I wasn't aware."
Speaking on Ref Watch on Your Site News, former Premier League referee Dermot Gallagher agreed with O'Neill and believed Trusty should have remained on the pitch.
"I think it is really harsh", he said. "The law says DOGSO (Denying an Obvious Goalscoring Opportunity) and the O is obvious.
"I think the referee on the field gets it right because the player is not in possession of the ball.
"He has a bit to go to get the ball and he's moving away from goal. He will get the ball eventually but I think the covering defender will get across."
Former striker Jay Bothroyd added on Ref Watch: "It's a possible goalscoring opportunity.
"The player is rapid, and his next touch will take him towards goal.
"I believe he would have got a shot off."
