Ferguson’s 70th birthday celebrations went flat as United fell behind to two goals from the Nigerian forward Ayegbeni Yakubu at Old Trafford on Saturday.
They managed to get back on level terms thanks to a double from Bulgaria striker Dimitar Berbatov.
But the champions’ lacklustre display allowed Blackburn back into the match and young Rovers defender Grant Hanley headed an 80th minute winner that denied United the opportunity of ending 2011 on top of the Premier League.
Ferguson has spoken recently of the impressive manner in which his side has responded to high-profile defeats this season, such as the 6-1 home loss to current leaders Manchester City.
He is now looking for the same response as United try to recover from a long list of injuries and illness before Wednesday’s visit to Newcastle.
“It was a disappointment, we couldn’t believe that. We never expected that result,” Ferguson said.
“We know we can improve on this performance. We won’t get many like that. I’m quite confident we will have a real go.
“We need to do it now, this is coming to the crucial time of the season. We have Newcastle away on Wednesday and want to make sure we come back with a proper result.”
United’s growing list of absentees forced Ferguson into fielding an unfamiliar line-up and the absence of Wayne Rooney, who did not even make the bench, compounded recent problems.
“Wayne hasn’t trained well this week,” Ferguson said. “He has missed a few days, but hopefully he will be back for Wednesday. He’s got little strains here and there.”
Ferguson started the day by revealing he aims to manage the club for a further “three years” before retirement but his weakened line-up ensured that it was a birthday to forget for the Scotsman.
Berbatov gave away a penalty for Blackburn’s opening goal; Michael Carrick and Phil Jones were badly at fault for the second and goalkeeper David de Gea was equally to blame for the late winning goal.
“We lost two terrible goals in the game and you can’t do that in fixtures like that,” said Ferguson.
“They are fighting for their lives of course and you expect them to put up that kind of fight.
“They were resilient and blocked shots really well all day, but if you lose goals like that, you give the other team a big opportunity to hang on.
“We have a lot of injuries at the moment and we had to gamble on Anderson’s fitness. He has been training very well for 10 days now, but throwing him back, it is not easy for him.
“He did his best, but it’s in that area where Michael Carrick and Ryan Giggs’s experience is missing at the moment.”
Under-fire Blackburn manager Steve Kean described the victory as his best day in football.
“It’s great to win at a place like this with the teams that have been built and the football that has been played here over the years,” said Kean, whose future has been the subject of widespread speculation.
“We’re desperate for wins and, with such a young side, this can be a real springboard to go and kick on.
Kean also called for a truce with the large section of Blackburn supporters who have vociferously called for his dismissal this season.
“The owners are behind me and the players are behind me. Now, I’d like to think there could be a truce between me and the fans,” he said.
“It would be good if the fans who have been negative will turn because we want Ewood Park to be a place where there is an intimidating atmosphere.
“I understand that what makes fans happy is the right results. They have seen those at Liverpool last week and again today. I am under no illusions.”