Neil Lennon accused some of his Celtic players of "behaving like spoiled kids" following their shock 3-2 Scottish Communities League Cup final defeat by St Mirren at Hampden.
Since taking over as Buddies boss in 2010, Danny Lennon had watched his side fail to take a point or even score a goal in their eight previous games against the champions, but on an afternoon of high drama they overcame overwhelming odds to book their place in the March 17 final against Hearts.
Debutant Esmael Goncalves, the 21-year-old Portuguese striker who last week signed on loan from Rio Ave, gave Saints the lead in the eighth minute, but that was cancelled out by Gary Hooper a minute from the interval.
Buddies keeper Craig Samson saved Charlie Mulgrew's penalty four minutes into the second half and things got worse for Mulgrew in the 83rd minute as he handled a Gary Teale cross inside the area, which allowed former Celtic man Paul McGowan to score from the spot before former Rangers striker Steven Thompson grabbed a third.
Mulgrew ended a desperate afternoon by scoring with the last kick of the match, but it was not enough to prevent Celtic slumping to their third successive defeat at the national stadium following last year's Scottish Communities League Cup final loss to Kilmarnock and a William Hill Scottish Cup semi-final defeat against Hearts.
And after seeing hopes of a domestic treble ended, Neil Lennon was scathing in his assessment of his side's performance and their mentality.
"I am bitterly disappointed with that performance," he said.
"It was soulless, it lacked intensity, desire and will to win, all the attributes this team has shown over the last six to nine months.
"That was an impersonation of a team that I know. There is not one player, maybe with the exception of Hooper, that would get pass marks today.
"There was a lack of discipline in our shape and play.
"I thought we were defensively awful, the decision making was poor and the there was a lack of quality in the final third.
"Some of them behaved like spoiled kids out there.
"The treble is gone, we have only ourselves to blame. The criticism is going to come our way and rightly so.
"Hampden seems to be a bogey ground, but to be fair that's the worst we have played here.
"I can take losing to Kilmarnock in the final and in the semi-final last year (against Hearts) because our performances were decent, but that was awful today from what I perceive to be top-class players.
"But maybe I have got it wrong and maybe I have to look at this week and change things, I don't know.
"I'd like to congratulate Danny and his team, he is a good guy in the game.
"I don't want to take anything away from them, but I cannot be too enthusiastic about our performance."
Neil Lennon was enraged that Mulgrew decided to try to place his spot kick.
The former Hoops skipper said: "I am sick of us missing penalties. I am sick of it.
"For some reason Charlie decided to side-foot it when I wanted him to put his laces through it.
"Charlie Mulgrew is the best dead-ball player I've seen for a long, long time, certainly in Scotland, and he is one of the best in Britain.
"I was amazed he side-footed it, I thought he would have whipped it or put a bit of power in it.
"Again, we seem to change our mentality when it comes to penalties.
"I don't know how many we have missed in my time as manager.
"I am not pointing the finger at Charlie because there was still a long way to go in the game.
"That was a game-changer, but our reaction was poor from the second and third goals onwards.
"We seemed to lose our discipline a little bit and it is not like us."
Saints boss Danny Lennon revealed he had prepared for his first win against Celtic by making his players watch a YouTube montage of famous Buddies victories against the Hoops which was sent to him by a fan.
He said: "What actually inspired me was that a fan had put together a lovely montage on YouTube of by previous St Mirren and Celtic games, I don't know the chap's name but he will know who he is.
"I had seen it prior to the Ross County game last week, it went way back to 1959 and showed great results like when they beat Celtic 3-0 in 1989 and through a fantastic result in 2009.
"The message behind that was to fuel the players with belief that it can be done.
"When you come into these games, you try anything, you will try something different and they didn't let us down. It was a fantastic effort from everyone.
"What was more pleasing was the manner in which we got the result, the players were different class."