New managers Manuel Pellegrini and David Moyes knew the importance of laying down an early marker in the title race.
United came into the game as defending Premier League champions, having responded immediately to City's 2011/12 title success.
But the Reds would leave the Etihad with their tails firmly between their legs as a rampant City dominated from start to finish.
Sergio Aguero's superb volley made it 1-0, and Yaya Toure added another before the break.
City raced out of the blocks after the re-start with Aguero and Samir Nasri making it 4-0 with only 50 minutes or so on the clock.
Though it threatened to be another demolition derby, City eased off the gas and Wayne Rooney's consolation was too little, too late for the visitors.
Enjoy our full match replay of this wonderful Manchester derby on the video above...
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