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 and Evra was angry to be denied a penalty by referee Martin Atkinson after being caught by Kolo Toure inside the box. The Frenchman showed his nous in a defensive role to help eradicate the danger provided by pal Tevez as the match swung from end to end but continued to get forward and misjudged a Rooney corner from a promising position.
With 12 minutes left, United advanced with menace again but Cleverley's cross was misjudged by van Persie, who could only head wastefully wide. City responded in kind as Silva showed great skill inside the box to allow himself plenty of space to fire goalwards but the ball cannoned off De Gea's shoulder and against the woodwork.
It was a let-off for the visitors and, after Tevez blazed over from another move instigated down City's right, Mancini threw on Edin Dzeko at the expense of goalscorer Yaya Toure. Sir Alex had to replace Valencia with Phil Jones and seemingly set the stall out for the closing stages but Zabaleta came up trumps with four minutes left.