Premier League - City humiliate United in derby
Evans saw red at 1-0, and shortly afterwards Balotelli plundered his second. Sergio Aguero added a third, before Edin Dzeko scored twice and David Silva once in a chaotic finale.
Darren Fletcher netted a lone reply for United, who conceded six in a home league game for the first time since 1930, when Newcastle went one better in a 7-4 win.
City now lead United by five points, but the symbolism of the result resonates far beyond the Premier League table. This felt like a changing of the guard, as the noisy neighbours stormed United's back garden.
Perhaps the most troubling aspect of an abysmal team performance from United was their late capitulation, conceding goals in the 89th, 91st and 93rd minutes.
Sir Alex Ferguson's sides never, ever, give up. Yet the total absence of defensive effort in the dying minutes suggests this one did exactly that.
City's combination of power and technical excellence - plus the depth of playing resources at Roberto Mancini's disposal - makes them deserving favourites for their first league title since 1968.
Though Richards looked ill-at-ease, James Milner tracked diligently back to help out his overworked team-mate.
The Spaniard has not made himself a leading Player of the Season contender through his defensive work, but he worked tirelessly when City did not have the ball.
Then came a sucker punch as James Milner pulled the ball back from the left past Silva to Balotelli, who stroked the ball perfectly into the bottom-right corner from the edge of the box.
What the strike lacked in power it made up in accuracy, and as David De Gea's net bulged the Italian stood stock-still and lifted his shirt to reveal a vest bearing the question: 'WHY ALWAYS ME?'
Because you're the only one launching fireworks out of your bathroom window, Mario.
However, City will take an indulgent view of their striker's foibles if he continues to deliver on the pitch.
The Italian's speed of mind and foot saw him steal a yard on Evans as he chased an Aguero through ball on 47 minutes. The Northern Irishman tugged him back - red card, no question.
And Balotelli increased his goal tally to six in five games as he finished a wonderful move on the hour mark - Silva took Anderson out of the game with a gorgeous spin in the box and Milner's cross gave the striker an easy finish.
Then came Aguero's turn to finish a flowing move. Balotelli backheeled for Milner, who slid the ball down the right for Richards, and the full-back's cross found Aguero six yards out.
Fletcher pulled one back with a magnificent finish from the edge of the box, but it proved to be the coldest of all consolation goals as City unleashed a late blitz.
Dzeko grabbed his first following shambolic defending of a City corner, before Silva finished through De Gea's legs from a Dzeko through ball.
Then the Bosnian helped himself to his second - City's sixth - latching onto a magnificent Silva through ball and finishing left-footed.
Ferguson's sides have bounced back from heavy defeats before - 5-0 to Newcastle and Chelsea, 4-1 at home to Liverpool - and cannot be written off.
One thing is beyond doubt, though. For the first time in the Premier League era, Manchester City are the team to beat.