Joleon Lescott refused to allow the added time controversy to become an excuse for City's first defeat of the season in a thriller of a derby at Old Trafford.
England centre-back Lescott and the Blues defence, so tight at the season's start, leaked four goals including a late, late Michael Owen winner scored in the 96th minute.
It cancelled out three City equalisers, including two superb efforts from the impressive Craig Bellamy that did not deserve to be overshadowed by that controversial finish.
Lescott said: "You're disappointed to lose any game - Craig scored two wonder goals for us and we thought we'd done enough to get a point, but it wasn't to be.
"There are no excuses. We are pros and we have to look at ourselves collectively and as individuals and realise that it just wasn't good enough.
"We look at each other and we've made mistakes. We started the season with four clean sheets and now we've conceded goals. We have to correct that.
"Last-minute goals are hard to take. We are gutted to lose as we did. Maybe we showed a bit of naivety towards the end. We're not a side to sit back. We want to win every game but sometimes you have to realise you can't."
Lescott is fully aware that the trip to the defending champions, hard on the heels of the 4-2 win over Arsenal, was seen as a litmus test for Mark Hughes' new-look City side.
He said: "A lot was made of this game beforehand, but you can't come to Old Trafford, concede four goals, and expect to get anything. We'll have to work on that in the week.
We knew the character was there. It's the first time this season we've gone behind and we've proved that we can come back and get ourselves in contention
"Their fans didn't go home thinking it was an easy game. We put them under a lot of pressure today and if we'd got the draw it would have been fully deserved.
"We believe in ourselves and we believe that we can push for honours this season. Arsenal came here and lost too. We still believe we can finish in the top four."
As Blues departed to regroup, Lescott added: "It's good that we've a Carling Cup tie against Fulham on Wednesday to put things right. It would have been hard to wait another eight days until the West Ham game."