Nottingham Forest were two goals to the good by half-time but allowed Bristol City to level in the second half at Ashton Gate before finally winning 3-2 and keep their Championship play-off hopes alive.
An angry Forest boss Billy Davies said: "I have used a very loud voice in the dressing room because we can't hope to get anywhere playing away from home like that.
"It's all about keeping clean sheets and we also need to be much more ruthless in front of goal to kill opponents off.
"The players didn't start the second half properly and I have let them know that.
"We didn't stop crosses or headers well enough and allowed Bristol City back into the game.
"The other side is that we could have had four or five goals with better finishing, but we are still a young team with a lot to learn and even after Luke's excellent goal we were not solid enough in seeing the game out."
City manager Keith Millen thought defeat was harsh on his players.
"We gave away two soft goals and gave ourselves a mountain to climb, despite being the better side in the first half," he said.
"I told the players at half-time that if they got an early goal the game was still there for us to win and that's how it panned out.
"We had some great chances and the winning goal has taken a deflection off one of our lads and looped into the only part of the net we couldn't defend.
"It was a cruel way to lose, but you can't afford to give good sides a two-goal start."