Bruce was visibly shaken in his post-match interview after United suffered their worst league defeat for more than three years.
And he did not mince his words when it came to assessing his side's King Power Stadium capitulation.
Speaking to Sky Sports, he said: "Unacceptable.
"We have to give the fans more to shout about.
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"The red card changes the game but we need to show some spirit and hunger.
"When things are tough you see what you have got - it was a one of them horror shows."
Bruce did leap to the defence of his players when accused of throwing in the towel by in a Sky Sports interview.
He said: "I think that's a bit strong.
"Up until today we have worked on defensive organisation to keep us in games.
"We have to do the basics well."