The Scottish Football Association have rejected Rangers' appeal against Kevin Thomson's red card.
Thompson was given his marching orders for a second-half lunge on St Mirren's Steven Thomson during Sunday's Co-operative Insurance Cup triumph.
The Gers waited until just before the 5pm deadline on Wednesday to lodge the appeal, in an attempt to make sure the case could not be dealt with before the game against Dundee United in the Scottish Cup on the same evening.
But the SFA were ready for such tactics and match referee Craig Thomson was poised to review footage of the incident.
The Ibrox player's suspension will begin immediately and he will miss the game against Dundee United.
A statement from the SFA said: "In accordance with the provisions for claims of wrongful dismissal, the referee, Craig Thomson, was requested to review the circumstances of Kevin Thomson's sending off for serious foul play against St Mirren in the Co-operative Insurance Cup Final match on Sunday, 21st March.
"The referee has indicated that he is content with his decision.
"Accordingly, the claim is dismissed automatically and will not be referred to
the review panel.
"The decision of the referee to send off Kevin Thomson is confirmed and the
player's automatic one-match suspension is applied, with 12 penalty points being added to his SPL disciplinary record.
"Furthermore, the player incurs a one-match fixed suspension from 4th April
for reaching the disciplinary threshold of 18 points."