Lee Clark was staggered after watching his Birmingham side fall to a heavy 5-0 home defeat to Barnsley.
The Tykes completely destroyed a disjointed City team, previously beaten only twice in 27 home games, with five goals in a 24-minute spell.
Craig Davies scored four goals 19 minutes as Barnsley produced a sensational second-half display to earn their first away points of the Championship season and give Lee Clark's Blues an evening to forget.
Clark said: "Losing any game at home is a massive disappointment but to lose by this margin is devastating.
"Any loss is tough to take but this one is very tough.
"We never started the game. We were lucky it was goalless at half-time in all honesty.
"It was a totally flat performance in every aspect. Barnsley played through us. It's an awful performance.
"There were lots of mistakes but everything we did was so flat. There was no urgency and it was lifeless.
"I said at half-time we had got away with it but we didn't heed the warning. We knew we hadn't performed.
"First and foremost, as the leader, I have to apologise to everyone associated with the football club for the performance.
"The players are an extension of me and try to mirror what I am about. But we looked as if we were disorganised and didn't play with any spirit.
"I have to take responsibility and the finger pointing starts with me.
"This result is a kick in the stomach.
"I do not take any credit away from the opposition. I thought they were magnificent."
The victory was only Barnsley's third win at St. Andrew's since October 1950, their first away win since January 14th and their best away success in 30 years.
And manager Keith Hill was understandably delighted with his side's success as they went above their opponents in the table with the three points.
He said: "There is no better result but we performed equally well against Blackburn in midweek and were beaten.
"I am really pleased for everyone who believes in what we are trying to achieve at Barnsley.
"Craig Davies takes the honours but this performance has been achieved from the groundwork he put in last season.
"You have to keep players to educate them and Davies is a mobile target man who scores goals. It's as simple as that.
"If we play through Craig Davies we will score goals. When he plays like he did against Birmingham then the relationship with (Chris) Dagnall, (Tomasz) Cywka and (Jacob) Mellis is evident.
"The game was going similarly to the Blackburn match when we dominated possession.
"On this occasion we really clicked and deservedly won the match.
"It was especially rewarding to me to see my side play so well.
"I have great belief in my players and I thought we could match Birmingham and out-perform Birmingham but didn't know we could get a result.
"I have gone through a lot of ups and downs to get the players I want to build a squad.
"It is essential we keep these players."