Sir Alex Ferguson admitted that Manchester United were made to pay the price for 'terrible' defending and branded their shock 3-2 Old Trafford defeat by Blackburn a 'disaster'.
Goalkeeper David de Gea was culpable for the winner 10 minutes from time when he failed to deal with Morten Gamst Pedersen's routine corner, allowing Grant Hanley to head home the winner after beating the summer signing in the air.
Yakubu had fired Blackburn, who started the day at the bottom of the table, into a shock 2-0 lead, with his opener coming from the penalty spot after 16 minutes following Dimitar Berbatov's pull on Chris Samba.
Berbatov did redeem himself to some extent with a well-taken brace to restore parity, but it was visiting manager Steve Kean who was smiling at the final whistle after a stunning success.
Ferguson, who was treated to a chorus of 'Happy Birthday' before kick-off, was in no mood to celebrate turning 70 by the time full-time arrived, with his side missing the chance to take over from Manchester City at the summit.
Disaster
"It is a disaster," the Scot said: "We never expected that. We've lost two terrible goals in the game, and we can't do that in a game like this."
After successive clean sheets from Anders Lindegaard, questions will now be asked over De Gea, who appeared to have recovered from his early season worries to reaffirm his status as United's No.1.
The Spain Under-21 star's culpability for Blackburn's winner seemed obvious, although Ferguson refused to apportion blame.
"We all could have done better," he said, when asked about De Gea. "It was a bad goal to lose."
Ferguson praised a resilient Blackburn side, adding: "They've defended for their lives."
Boggy
The United manager said his players had struggled on a heavy pitch.
"I think they found the speed of the pitch not so good, it was really heavy rain all week and it made the pitch really boggy."
Ferguson admitted when United got back to 2-2 he thought they would take the victory.
"I thought at that point we were set to win it," he said. "We've got injuries at the moment but we had to take a gamble on Anderson's fitness. He did his best."