Manchester United striker Wayne Rooney was left to reflect on another poor performance after admitting the team had lost their Old Trafford "fear factor".
Just over a week after describing their 3-0 defeat by arch-rivals Liverpool as one of the worst days he had ever had in football, the England international found himself trying to explain a similar scoreline at home to neighbours City.
Asked why they had lost a sixth Barclays Premier League match at Old Trafford this season - more than in the previous three campaigns - Rooney said: "I don't know but it's not good enough.
"We can't lose six homes games in a season and we have to put that right and make this a place teams fear again.
"We know we have to respond. It's a bad night for us all but we have to move on."
United got off to the worst possible start as Edin Dzeko scored after just 44 seconds and the City striker doubled the lead after the break before Yaya Toure rounded off victory in added time.
Rooney added on MUTV: "We didn't deserve to win. We weren't clinical enough and we didn't create enough chances.
"No-one likes to lose a derby game - they're big games and they're great to win, but when you lose it's not a great feeling.
"It was a poor start - I'm not even sure whether we touched the ball before they scored.
"After that, I thought we did okay and got back into the game a little bit but their second goal was a killer."
Manager David Moyes continues to shoulder the blame for the defending champions' disastrous season.
He insists work has begun to accelerate the transition from Sir Alex Ferguson's reign to his own but insists it will take a while for that to take effect.
The Scot is hoping, however, it will not be a rebuilding task which takes too long.
"I thought it would be a tough year for us, no doubt about that, but I hoped we would be much more competitive and closer to the top of the league than we are at the present time," he said.
"Everyone knows this is going to be a job which is going to take a little bit of time to get the way we would like it but that is the job and I recognise that.
"It is under way in its own way. You don't just suddenly change things around.
"A lot of other clubs have had to change and they have had to do rebuilding jobs and look at the time it has taken them to do that and get to a level of competing.
"We hope it won't take us as long as some of those clubs have taken.
"I think we have got a period of time where we are going to have to make sure we get to that level which we are not at just now."