injury with Kolo Toure taking his place. Undoubtedly, it was another boost and Hart had to race from goal to prevent Young from reaching a van Persie through ball.
Sergio Aguero somehow worked his way through four defenders but could only manage a tame side-foot shot that De Gea comfortably fielded and, six minutes later, another rapier thrust by the Reds again had the desired effect. Valencia picked out Rafael on a typically energetic burst forward and Rooney advanced smartly onto the Brazilian's pull-back to clip another clinical finish wide of Hart.
A furious response was expected but, aside from a scare when Gareth Barry choked his shot from the centre of goal two minutes before the break, the Reds looked assured as the half ended and good value for the two-goal lead.
Some defensive reorganisation for United was required when Chris Smalling replaced the injured Jonny Evans while Roberto Mancini withdrew the ineffective Balotelli in order to hand Carlos Tevez another chance to upset his former club. Although Cleverley smashed a half-chance over the bar, City started to build up a head of steam with Aguero sending a decent dipping attempt off target and Rio Ferdinand needing to defend a dangerous Samir Nasri cross brilliantly at the far post.
The whole complexion of the game changed around the hour mark as United had a goal erroneously ruled out for offside. Van Persie bent a beautiful right-foot shot against the inside of a post with Hart well beaten and Young's rebound was disallowed, even though replays showed Zabaleta was playing him onside. Within a matter of seconds, instead of being 3-0 down, City reduced the deficit despite the best efforts of De Gea. The Spanish keeper made a superb double-stop to thwart Tevez and Silva but Tevez showed great composure to tee up Yaya Toure for a precise finish not disimilar to Rooney's two efforts.
United gamely tried to use attack as the best means of defence