Phillip Cocu felt Derby County were unlucky to lose to Nottingham Forest as he was left to rue Jayden Bogle's costly mistake.
Lewis Grabban got the only goal of the game in the early in the second half after he capitalised on Bogle's terrible pass.
Cocu was pleased with many aspects of his team's play, but admitted the mistake was critical.
"The boys did well and they started well. Defensively we were strong," he said.
"We had a great chance for Tom (Lawrence) - it was a good save. I can't be satisfied how we came out second half in the first 10 or 12 minutes.
"In the big games, in many games but especially in games like this, a detail, a mistake, bad judgement or sometimes class can make the difference.
"Today, the mistake of Jayden cost us the result.
"That is tough because I think we played quite a good game.
"We had good presence and played good football over a large part of the game.
"We created a good few opportunities, and deserved more than a 1-0 loss."
Defeat left the Rams 16th in the Championship, seven points behind fifth placed Forest having played a game more.
