As Yaya Toure bludgeoned Newcastle into submission on Sunday afternoon, bitter Manchester United fans resigned themselves to Premier League defeat.
The disappointment of City's victory was all the more acute as Toure personified exactly what United have been missing this year, an imposing creative midfielder capable of dominating top-flight matches.
Premier League glory, or glory of any kind, has proved elusive this year and for a United team conditioned to win, the pain of this year's collapse will linger long in the memory. However, next year represents a second chance and a new, tougher test for both Manchester clubs.
Teams have challenged the United juggernaut in the past. City themselves are the most recent incarnation of a Chelsea side who pinched trophies from Ferguson in the mid-2000's. Before Chelsea there was the Arsenal 'invincibles', and before that Blackburn tested the mettle of the Red Devils.
Each and every time Ferguson saw his side defeated by these sides, and each and every time he regrouped, reassessed and returned his side to the top. Mourinho's Chelsea supposedly signalled the end of an era for United, winning back-to-back titles in 2005 and 2006, but Ferguson bit his lip and bided his time.
That lean spell allowed Ferguson to create arguably his greatest United team. The United boss brought in Ronaldo, Rooney, Evra, Vidic and Tevez as the Red Devils won three Premier League titles, one Champions League and a League Cup over a glittering four-year period.
Over a 10-year or 20-year time span teams experience peaks and troughs in their quest for success. Barcelona have shown that no team, however superior, can win indefinitely. But Ferguson's secret has been to maximise the peaks and minimise the troughs. Each time United get knocked back, they return the following season to pick up a trophy.
In 2005, Mourinho guided Chelsea to a record Premier League points tally, leading many to declare a new era of west London dominance had arrived, bank-rolled by the bottomless pockets of Roman Abramovich.
For Chelsea, now see Manchester City, and while City certainly pose the toughest test yet, it is still one Ferguson has seen before. City's owner bestows limitless budgets and United now emerge black-eyed and bloody-nosed from transfer battles with their closest rivals - the pursuit of Samir Nasri was the most recent dent to United's pride.
But Ferguson has rebuilt teams in the past and the pieces are already in place for Fergie's next title-winning Old Trafford side. The United boss forked out almost £50m on Phil Jones, Ashley Young and David de Gea last summer, three players who will form the basis of a United team for years to come.
Following Sheikh Mansour's arrival, the United manager recognised his side could not compete with a team that could afford to spend £75m on Joleon Lescott, Emmanuel Adebayor and Carlos Tevez. The Abu Dhabi purse allows purchases beyond that of the Glazers, who run the club with such restraint and frugality that many fans have become impatient with their inaction. But a conscientious approach to boardroom affairs could stand them in good stead when the financial fair play rules come into force in 2014.
Such an approach can also pay dividends - to shareholders as well as fans - as Ferguson responded to their last trophyless season in 2005 by bringing in Patrice Evra, Nemanja Vidic and Edwin Van Der Sar for a combined £15.5m. Ferguson may irritate with his continued insistence on finding "value" in the transfer market, but his dealings demonstrate that the concept certainly exists.
One of those signings, Patrice Evra, believes that City's rise this season does not signal the beginning of the end for United.
"I know that if we don't win the league then a lot of people will say this is the end of the empire and ask how will survive," said Evra. "But there's a lot of talent at this club and we've had to deal with a lot."
The Manchester United left-back hinted that last season's summer represented something of a transition for the Old Trafford club, which makes the fact that they were still able to mount a title challenge all the more impressive.
"We lost players like Edwin van der Sar, Gary Neville and Paul Scholes. It's never easy to find a solution immediately, but it's not over yet. I'll say it again: we're not dead."
The problem for United is that they did not replace Giggs and Scholes either. Evra is one of several United stars on the wrong side of 30 but while Giggs and Scholes are preparing their coaching tracksuits, Ferdinand, Vidic, and Carrick will continue to occupy key roles next season. Experience is an important component of any side but obvious holes remain in the Old Trafford squad list.
Central midfield is still a problem one year on and Ferguson should strike early. This summer's Euros will hinder moves for the majority of Europe's top talent and Arsenal and Chelsea have acted swiftly to secure transfer targets, Lukas Podolski and Marko Marin respectively. United should do likewise.
But it would be wrong to suggest the situation is desperate. Ferguson's squad is packed with young talent, setting them up for campaigns to come. Jones, De Gea, Evans, Anderson, Smalling, Hernandez, Welbeck, and Cleverley are all first-team players under 24 while Rooney, Nani and Valencia are only 25 and 26 years old.
Ferguson has talked about adding "two or three" new faces this summer, with the highly-rated Japanese midfielder Shinji Kagawa and Ajax captain Jan Vertonghen strongly linked. Such signings would satisfy the fans demand while allowing Ferguson to stick resolutely to his transfer policy.
In the past it has worked out superbly, often returning United to the summit of English football as swiftly as they had been dethroned. Their longest league drought, from 2004-2006, saw them go three years without a Premier League title.
They responded with three on the bounce in such a style that few could see how they could be beaten. But the very nature of football ensures that no side can win forever. Ferguson has proved himself as the Premier League's greatest manager precisely because United remain a constant while others rise and fall.
This season has seen the blue moon rise to new heights at the expense of their city rivals and the league has been a two-horse race since early February. Liverpool and Arsenal look incapable of a title challenge next year, and Chelsea face a transitional year of their own. So Evra is right, the United empire is not dead yet but his side need signings this summer to resuscitate the ageing parts of their squad.
Last week the "supermoon" shone brightly across Britain - after last Monday's derby defeat it was surely a blue moon. Ferguson now faces a mighty challenge to eclipse City's achievements but no manager has proved more adept at rising to such occasions.
Kagawa's signing hints at the pieces falling into place and history suggests Ferguson will assemble another squad capable of securing a swift return to the top before the summer is out. He's done it before and there's no reason he cannot do it again.