Sabri Lamouchi said his Cardiff City players "lost their minds" during a dreadful four-minute spell in which they conceded both goals in the 2-0 defeat by Norwich City.
Cardiff started the better of the two sides for the first 20 minutes or so, but Lamouchi said the Bluebirds "gifted" two goals to the Canaries which ultimately decided the tie.
"It's difficult to analyse the game. To start in this way, to disturb Norwich here, at home, in the first half an hour, we created and I think we deserved to score first," he said.
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"Then we lost our minds and give them two goals in only a few minutes.
"In the break, I needed to do something different. Change the striker and the team, because I believed that with one goal we have a chance to come back into the game.
"Unfortunately in the second half, we didn't create a lot. But I have some regret."
Cardiff had good early chances through Connor Wickham, Jaden Philogene and Mahlon Romeo, while Ryan Wintle and Perry Ng both had good opportunities after the break.
The difference, Lamouchi said, is that Norwich take those chances and Cardiff, ultimately, didn't.
"When you create chances, you need to kill them. But we didn't score and that's why we are the worst attack in the league," he added.
"We need, absolutely, to work on this situation. It's about consistency, during the game and during the season. We are playing Norwich, they were in the Premier League not long ago, they have good players.
"If you give them something, there's immediately a sanction, that's the difference."
Cardiff continue to hover above the relegation zone, although after the highs of two wins, the loss at Carrow Road will doubtless bring the Welsh side back down to earth.
Asked if he thought he had enough firepower, despite the clear deficiencies in front of goal, to stay afloat, Lamouchi replied: "Absolutely. You can't come here to play the way we played and disturb them if you don't have a minimum quality.
"Just believe, change the mind and be more determined. When you have half a chance you need to score, if not, don't give anything. We can finish the game with a clean sheet.
"But we can't think we are better than what we think."
The only saving grace as far as Cardiff are concerned is that all the other teams from 16th and below lost on Saturday, with Rotherham United playing Swansea City on Monday.
"I will look (at the other results) after the press conference," the manager said. "But I was disappointed. Because we were probably thinking, after winning two games, we are better than that.
"But no, we are where we are. We will fight until the end to save the club and get three teams behind us at the end of the season. That is our goal."
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