The Noisy Neighbours are really big noises now, deafeningly so.
On a night of great tumult and significance at the Etihad Stadium, Manchester City seized the initiative in the race for the Premier League title with Vincent Kompany's header punishing Alex Ferguson's costly cautious Plan A.
City are now top, leading through a +8 goal-difference.
For a club of United's great attacking tradition, Ferguson's 4-5-1 approach was deeply disappointing. Wayne Rooney was too isolated, threatening properly only when Danny Welbeck arrived after the hour-mark.
The champions became fractious, Ferguson even squaring up to Roberto Mancini.
These two heavyweights went toe to toe, on and off the pitch, the pressure cranking up as the clock ticked down. "The noisy neighbours are getting louder Alex", read one City banner. "Fergie's cracking up,'' chanted the City fans while exhorting their team to hold out.
Good performances were seen throughout City's side, from Kompany, Gael Clichy and Gareth Barry to Samir Nasri and Yaya Toure, but United fans will reflect long and hard on their manager's approach.
United had been within touching distance of half-time, so close to Ferguson's cautious first-half game plan, but one mistake cost them.
Chris Smalling and Rio Ferdinand had defended so ably until then, clearing all the danger that came their way, reacting sharply on the ground and in the air. This was defiance and tactical discipline writ large. For 45 minutes but not injury-time.
When David Silva drilled a corner across, United responded too slowly. David de Gea came from his line but ran into traffic, leaving his centre-backs to deal with the danger. Smalling seemed distracted by Joleon Lescott, allowing Kompany the yard of space to muscle in and power an unstoppable header in, totally changing the mood. Suddenly the home nerves were swept away.
United's Plan A had failed. When the team-sheet had appeared it was a surprise to see Ferguson had flooded midfield, inserting Ji-sung Park and Ryan Giggs alongside Nani, Paul Scholes and Michael Carrick, leaving Rooney as the tireless frontrunner. It looked timid, a game plan built to frustrate rather than forage for goals.
For the opening 20 minutes, United's tactics worked before City began building, before Nasri began getting on the ball. The Frenchman was excellent. So were the fans, whipping up a magnificent atmosphere.
City fans reminded their visitors of the 6-1 rout at Old Trafford. "You lucky b******s, it could have been 10," they sang, also saluting Mancini with gusto. The tempo was frantic, the game thudding from end to end, sending all these chants spilling down from the stands.
United had started strongly, Rooney threatening, then back came City.
Silva's effort was blocked by Smalling. This was breathless fare, hardly of great technical quality but compelling none the less.
The noise rarely ebbed. Howls of abuse swirled around the Etihad when Scholes deliberately handled Barry's forward pass, escaping a booking from Andre Marriner. United were working so hard, stretching every sinew to be first to the ball. Ferdinand nicked possession off Carlos Tevez. Park slid in to intercept the ball as it headed towards Barry.
Yet City increasingly saw more of the ball, increasingly looked to find gaps. After 14 minutes, Nasri found Tevez down the inside-right channel, requiring a great clearance from Phil Jones, United's right-back. Still United's repossession worked. Still they pressed high up the pitch, Park and Nani flying out from midfield to close down City defenders when they attempted to build, frequently forcing them to hit long. They hunted the ball with an inordinate hunger. This was chess with sweat.
Such was the speed of play that Marriner was caught out. Kompany challenged Rooney for the ball, the England striker actually caught the Belgian with his right foot, falling to the ground. Kompany was unfortunate to be booked.
The sense of City growing in confidence was unmistakable. In a game of such fine margins, any mistake threatened embarrassment. When Rooney miscued a clearance, Pablo Zabaleta and Lescott teed up Aguero, who shot wide.
Aguero's father-in-law, Diego Maradona, leapt from his seat in anticipation, then annoyance.
All around Maradona, banners fluttered in the breeze. "Some might say, we will find a brighter day" read one, borrowing from the songbooks of City's most famous fans. Mancini's players were working hard for that new dawn.
Nasri tricked his way past Evra but Ferdinand cleared. Rooney, as often when he is isolated, became fractious, lecturing Marriner, especially when Tevez miscontrolled the ball and followed through on Jones. Jones then bodychecked Clichy.
Nasri was excellent, setting up Aguero, who was closed down by Ferdinand.
Another blue wave poured forward, Aguero scampering through but Smalling stayed calm. City fans were loving it, even breaking off from their diving impressions as Ashley Young warmed up. Whistles of derision followed Rooney around.
Then there was applause as Zabaleta's cross hit Evra and went off for a corner. Silva delivered but Evra cleared. Silva delivered again, and there was Kompany sending the Blu Moon rising high.
Ferguson still did not switch at the break, waiting 15 minutes before removing the disappointing Park for Welbeck. Buoyed by Welbeck's running, United seemed more themselves, more in tune with their attacking traditions. Nani slipped the ball right to Jones, whose cross was cleared by Lescott. Jones' next cross was shocking, over-hit.
Mancini responded midway through the half, removing Tevez, introducing Nigel de Jong. Mancini was demonstrating his pragmatic streak, bringing more bite to midfield with Toure pushing on.
The game briefly became fractious, Jones diving in and catching Barry.
Rooney was still appealing for every decision, even imaginary ones. The players were giving everything, the sweat dropping from Toure's forehead yet he almost put City further clear with a strong drive that flew just wide. Toure was a monster in midfield, making light of Scholes' foot up, although angering Ferdinand and company by waving an imaginary card.
Such were the stakes that the challenges really flew in. De Jong's legs tangled with Welbeck's, leaving the young England international writhing on the ground. It was not malicious, more clumsy but brought a yellow.
Ferguson was enraged, shouting at Mancini, who responded, the pair going head to head until David Platt intervened. Still the tackles went crashing in. Carrick clattered Barry.
City could have made it 2-0 but De Gea did brilliantly to deny Clichy.
Ferguson had unleashed other attackers, Antonio Valencia and Ashley Young, but it was too late. Ferguson's tactics had failed. (© Daily Telegraph, London)