THIS was a result to make football itself stand up and cheer.
And not just because the Bad Guys got a punch on the nose from the Good Guys.
This was also a victory for the vibrancy of youth. And for the way teams and clubs should be built.
Best of all, this was a victory for having the balls to go out and play attacking football when you are staring down the barrel at a huge, embarrassing defeat.
City boss Roberto Mancini, in comparison, took off striker Mario Balotelli and sent on defensive midfielder Gareth Barry with the score at 2-2.
That told you everything you needed to know about the philosophy of the two managers.
At the end, Alex Ferguson went over to pay homage to the travelling United fans before finishing it off with a bow.
Minutes earlier, he had risen excitedly from his seat to acclaim the goal from Nani that had seen United come back from two goals down to win the Community Shield - and exact some revenge for their FA Cup semi-final defeat by their nearest and dearest.
The look on his face said 'How do I do it? Am I a genius? Or is it just luck?'
Whatever it is, even in his 70th year, Ferguson still has it.
At half-time, United were 2-0 down to a City side they had largely outplayed courtesy of a couple of mistakes by new £18million keeper David De Gea.
The second, when the former Atletico Madrid keeper was first out of position and then horrendously late getting down to a speculative 25-yarder from Edin Dzeko, was an absolute belter.
De Gea had arrived to tributes from all and sundry, with Liverpool's Pepe Reina saying: "He is the future of Spain, an incredible keeper who will improve even further in England."
Real Madrid's Iker Casillas heaped more praise on the 20-year-old with the words: "He'll retire us all."
Suddenly, though, we were once more hearing the name Massimo Taibi while De Gea attempted to hide behind his beard.
Ferguson's reaction was to haul off Rio Ferdinand, Nemanja Vidic and the hopeless Michael Carrick.
In place of his three most experienced men came Phil Jones, Tom Cleverley and Jonny Evans.
It was a mixture of throwing in the towel and damage limitation in that Ferguson was now admitting 'Yes, it IS a meaningless friendly - and here come the kids to prove it'.
Yet within 12 minutes a team of comparative greenhorns had drawn level and scored the sort of equaliser that was patented at London Colney. It was pinball wizardry, with Nani starting and finishing the move after deft touches from both Wayne Rooney and Cleverley.
Such was United's dominance over a City side that did little other than score their two goals that United won the possession battle 63 per cent to 37 per cent.
Most encouraging for Ferguson will have been the fact that the oldest man in the side who played most of the second half was Ashley Young, at 26.
The others were De Gea, Chris Smalling (21), Jones (19), Evans (24), Rafael (21), Anderson (23), Cleverley (21), Nani (24), Rooney (25) and Danny Welbeck (20).
And they were still missing Javier Hernandez, 23.
What riches for United fans. What a testimony to the way Ferguson keeps rebuilding.
In the blink of an eye, he seems to have moved on from one dynasty - that of the retired or departed Neville, Scholes, Brown, Van der Sar and O'Shea - to another.
What a contrast to moneybags City whose main aim in life seems to be to buy every player not wanted by Barcelona or Real.
While there was a warm feeling about United yesterday, City left you cold.
They were intent on intimidating United from the start with the deranged Balotelli starting it all by going head-to-head with Vidic.
Dzeko was then booked for a late tackle on Anderson, whose reaction also bought a booking, while Micah Richards should have been sent off for a studs-up effort on Young.
Yaya Toure then saw yellow for moaning and play-acting and it was only a matter of time before Nigel de Jong came skidding in both late and from behind on Welbeck.
It made you think that if a team is built in its manager's likeness then Mancini, on yesterday's evidence, should be as ugly as sin.
City then rubbed salt in the wounds by scoring not once but twice, the first when Joleon Lescott got in behind Ferdinand and Vidic to head past De Gea, who had come charging off his line only to freeze when he decided he couldn't get to the ball.
The second, as we know, was a disaster.
And yet, 45 minutes or so later, it was the turn of the City end to empty and leave it to their own now raucous neighbours after a blunder by Gael Clichy and Vincent Kompany allowed Nani to set off on a run covering half the pitch that finally saw him round Joe Hart for the winner.
What a result for United both in the short and long term - but spare a thought for poor, old City.
They've only got Carlos Tevez and Sergio Aguero to throw at the problem. For today anyway.
