Manuel Pellegrini's title-chasing side ran riot against its neighbor, with Edin Dzeko netting a brace and Yaya Toure rounding off the 3-0 rout late on.
|MAN UNITED LATEST
United fans later vented their anger at Ferguson, who hand-picked David Moyes to become his successor.
The legendary former manager was subjected to fierce questioning from the home support, while Moyes was also verbally abused by a number of fans.
In the first signs of open revolt at Old Trafford, stewards were also forced to guard the Stretford End's 'Chosen One' banner in case fuming fans attempted to tear it down.
Moyes later stoked the fans' ire by claiming United must "aspire" to reach City's level in the near future – despite beating the team to the league title by 11 points last season.
He told reporters after the game: "I think we've played a very good side and it's the sort of standard and level we need to try and aspire to get ourselves to at this moment in time."
City, meanwhile, strengthened its own title bid with the victory, as the club currently sits three points behind table-topping Chelsea with two games in hand.