The Glasgow outfit had a string of close encounters with opening the scoring at Easter Park this afternoon, but an additional 30 minutes of play was necessary to determine a victor. The clash looked destined to be decided by a penalty shootout before John Baird pounced with the winner on 117 minutes to earn the trophy for the Championship side.
"I'm extremely disappointed as you can imagine, as are the players," he told reporters. "The game itself, we didn't play well but I thought we had the better chances.
"When you don't take them you obviously run the risk of losing a goal and that's the way it worked out."
McCoist's men have already been crowned League One champions this season.