Manchester City ensured United would have to wait a little longer to claim the Premier League title with a hard-fought 2-1 win at Old Trafford.
But Sir Alex Ferguson's team remain 12 points clear at the top and this defeat may only delay United's celebrations.
City took the lead through James Milner, whose powerful shot wormed its way past David de Gea, before a Vincent Kompany own goal restored equilibrium just minutes later.
But it was the away side who struck the decisive, final blow through substitute Sergio Aguero, whose vicious near-post effort rocketed into the top corner.
Wayne Rooney returned in attack for the Red Devils, partnering Robin van Persie up front, while Phil Jones was named in defence. Veteran Ryan Giggs was selected to appear in his 37th Manchester derby.
Ex-Red Devil Carlos Tevez spearheaded City's attack, with Aguero only fit enough for a place on the bench, while captain Kompany lined up in the centre of defence.
The game started at a frenetic pace, with both sides hurtling forwards and City especially eager to reclaim local pride and spoil the Old Trafford party. The away side's right flank was particularly dangerous, with Milner fizzing crosses into the box.
But after the frantic early exchanges, the game settled into a calmer, more measured pace. City came closest to opening the scoring, with David Silva collecting Kompany's crossfield pass, but the Spaniard’s pull-back was thumped clear by Jones.
In a half of few chances, it was adventurous full-back Rafael who had the home side' best effort.
The Brazilian latched onto Van Persie's flick-on, but his looping, poked finish hit the outside of Joe Hart’s near post – though the England keeper looked to have it covered.
United began the second half well but it was City who struck first, lighting the blue touch paper.
Gareth Barry robbed Giggs in midfield and burst up the left flank before squaring the ball to Samir Nasri on the edge of the box.
The Spaniard then teed up Milner, whose powerful effort flicked off Jones and flew into the net to give City a 51st-minute lead.
But the advantage lasted just eight minutes. Van Persie, in the midst of a goal drought, turned provider to send in an inch-perfect cross towards Jones, with the defender heading the ball against Kompany and into the back of the net.
The play dulled somewhat after that goal rush, until substitute Aguero produced a moment of magic. With few options and being pushed further and further away from goal, the Argentine finally unleashed a ferocious shot that thundered into the roof of the net.
United tried to mount a response but it was in vain as City clung on to claim a morale-boosting win which delays the Red Devils’ wait for a 20th championship crown.