Neil Harris slammed the defending of his Millwall side as they threw away a 3-2 lead at Norwich City to lose 4-3.
The Canaries scored twice in stoppage time to maintain their promotion push.
For the Lions it means they have still not won an away game this season.
Harris said: “I’m extremely disappointed at the lack of professionalism to see the game out.
“The positive is that we scored three goals away from home. But I can’t comprehend the defensive display I’ve just seen. At 3-2 up after 90 minutes we have gone to a back five to help the defence as a unit. We’ve conceded two goals. My daughter is six years old and plays U7, if they conceded goals like that I’d be disappointed.
“It is a bit damning of the team. But I’m the captain of the ship – I take responsibility. Individuals have to hold their hands up – it’s not acceptable.”
Asked if Jordan Rhodes’ equaliser to make it 3-3 was offside, Harris replied: “Onside. My defenders need to take up better positions.”