Sir Alex Ferguson admitted Norwich deserved their 1-0 win at Carrow Road which denied Manchester United the chance to go back to the top of the Barclays Premier League.
After Manchester City had thrashed Aston Villa 5-0 earlier on Saturday afternoon, only a win would have been enough for United to jump over their neighbours once again.
However, with England striker Wayne Rooney missing because of tonsillitis, the Red Devils produced a lacklustre display as the Canaries produced another composed display to secure a third win in five Premier League games with a fine header from Anthony Pilkington, once on the youth books at United, on the hour.
"Norwich deserved their win because they worked so hard for it, although we had a lot of possession and one or two half chances. We didn't create enough great chances. It just wasn't our night," Ferguson said on ESPN.
"Their goal was a marvellous cross and a great touch for the header. There was nothing our keeper could do about that. So you have to give credit to Norwich because they battled well, and their goalkeeper had a good night as well, so it is disappointing."
Ferguson continued: "You always feel that we can do that [come from behind to win] because the history of the club is like that - players have gotten used to making comebacks and we are always a threat in the last few minutes of matches.
"We were tonight in some respects, but they defended really well and the goalkeeper made some saves at vital moments."
Manager Chris Hughton, appointed in the summer after Paul Lambert left for Villa, felt this performance was the most satisfying of the campaign so far, with a third win in five league games, which have included four clean sheets.
He said: "It is, simply because it is Manchester United. They tested us more than anybody we have played against and were resilient enough.
"I suppose with the run we are on, the confidence we have from that we were able to show. It is certainly a wonderful achievement."