The win leaves Roberto Mancini's side five points clear of the champions but the manner of the performance and scoreline has caused shockwaves on the red half of Manchester with some suggesting the balance of power is now shifting. Those following the FA Cup betting odds may be wondering if the side can make a clean sweep of things this season, though United will be determined to stop them.
Fletcher admits the huge defeat is particularly difficult to stomach and feels for the United fans who will be subject to ridicule from their City counterparts.
He told MUTV: "Without doubt we realise how much stick and how much banter there will be for our fans.
"We know how much it is hurting, the players are hurting just as much.
"We have to live in the city as well so we are going to have to deal with it as well."
Fletcher, who scored United's consolation in the game, says they must bounce back from the heavy loss but conceded that may not necessarily be easy.
"We are disappointed, really disappointed, but we will have to bounce back.
"It is a problem to bounce back from a scoreline like this - nobody wants to lose by the margin we did."
United are next in action when they go to Aldershot in the Carling Cup on Tuesday and the football odds make them strong favourites to win.
However, boss Sir Alex Ferguson is likely to field a much-changed line up with the likes of Michael Owen, Dimitar Berbatov, Federico Macheda and Antonio Valencia among those set to get a run-out.