SEAN O'Driscoll admitted Forest produced their worst performance of the season at Ipswich and refused to make excuses over their 3-1 defeat.
Referee Andy D'Urso's decision to award a soft penalty following Danny Collins' challenge on DJ Campbell was the turning point of the game, as Luke Hyam smashed home the rebound after Campbell's spot kick had been saved brilliantly by Lee Camp.
That made the score 2-1 just five minutes after Dexter Blackstock had cancelled out Guirane N'Daw's opener, which came after a mistake from Camp – who could also have been sent off in the first half.
Daryl Murphy killed the game off with a third Ipswich goal in the 90th minute – but O'Driscoll admitted his side had not deserved a share of the spoils.
"We got a great result against Wolves and the one thing we said after that was not to get complacent now… but talking about it does not do it, it is about what you do on the pitch," he said.
"And we committed all the mistakes that you don't want to commit on the pitch.
"We gave the ball away from the kick-off, we did not defend the first goal kick… we gave them momentum and never wrestled it back from them.
"I am glad we did not get somebody sent off, because that would really have capped off our night.
"What do I put it down to? We are not as good as people think we are. We conceded 11 crosses against Wolves and we could have conceded three or four goals then.
"If, individually, you have poor nights, you make sure that you are still hard to beat as a team, but we were not even that.
"When you have an off night, you try to make sure that you get something out of the game. It was disappointing."
O'Driscoll refused to gloss over Forest's performance in general, saying: "Sometimes the scoreline does not reflect the game – but that one did, if we are honest. It could have been more, to be fair.
"We started badly and got worse. We were thinking about making changes early, in the first half.
"But that is the worst we have played all season. That is not typical of the Forest team we have seen this season."
O'Driscoll also revealed that Simon Cox is likely to be out for two months with his ankle injury, which further scans have revealed does involve a fracture and a detached ligament.
"He will have another scan in a few weeks to see if it is healing, if it isn't, he might have to have it pinned," said the manager. "If it is healing, it is still going to be six weeks beyond that, probably."