Sir Alex Ferguson praised opponents Norwich but did not blame his Manchester United players for their
shock 1-0 defeat at Carrow Road.
A below-par United, who led the Premier League table at the start of the day, went down to a second-half Anthony Pilkington goal.
"They deserved the win because they worked so hard for it," Ferguson said.
"They defended really well and their goalkeeper made two or three really good saves at vital moments."
England number two John Ruddy was in goal for the Canaries and made notable saves from Ashley Young and his own defender Sebastien Bassong.
But despite going a goal down - the 11th time in 18 matches this season - Ferguson was hopeful United would salvage something from the match.
Norwich win over Manchester United very special - Chris Hughton
"The players are used to making comebacks and we're always a threat in the last minutes of matches," added the veteran manager.
"We had a lot of half-chances but it just wasn't our night."
United are now second in the table, a point behind neighbours Manchester City.
Meanwhile, Canaries manager Hughton said his side "earned" the victory - their third in five matches.
"This is very special," he told BBC Sport, with his side now 13th in the table and unbeaten in the league since 6 October.
"When United come to town it's always a massive occasion because of the history they have.
"The most pleasing thing about the win is that we earned it. They put us under a lot of pressure, but our back four were excellent.
"We were bad at
home to Liverpool
away to Chelsea.
I wanted a response from the team and I got that."
Hughton also heaped praised on keeper Ruddy.
"He was outstanding," added the former Newcastle and Birmingham manager.
"Even when he didn't have saves to make, his concentration was very good.
"There were moments when we really needed him. For a keeper, it's about keeping concentration levels up."