After conceding two goals to Yakubu either side of half-time - the first one a penalty - the Reds battled back magnificently to draw level courtesy of a double by Dimitar Berbatov. However, Grant Hanley scrambled a late winner for Rovers against the run of play to ensure the champions finished 2011 on a low note, missing out on the chance to go top of the table.
United's injury problems led to Rafael and Ji-sung Park forming a makeshift central midfield partnership with Michael Carrick continuing in defence. Rovers had problems of their own with David Dunn and Junior Hoillett adding to the list of absentees.
Steve Kean's side didn't start like a team at the foot of the table as they passed the ball around with composure while the Reds started with unusual lethargy. Nani sent a left-footed shot wide and Carrick was squeezed out by Mark Bunn at the near post from a Nani corner but Paul Robinson's deputy in the Blackburn net was rarely troubled.
Disaster struck when awkward customer Chris Samba was felled inside the box as he grappled with Berbatov following a long free-kick by Bunn. Mike Dean had no hesitation in pointing to the spot and Yakubu nervelessly sent David De Gea the wrong way to stun Old Trafford with 16 minutes on the clock.
United's response was muted. There was a shout for another penalty when Patrice Evra was sent flying by Radosav Petrovic and man-mountain Samba got his head in the way of a Danny Welbeck drive but the Reds were showing little of the sparkle of the recent fixtures.