Ask any senior Manchester United figure and they will tell you that losing the Premier League title to Arsene Wenger's Arsenal or the Chelsea sides of Jose Mourinho and Carlo Ancelotti was a pleasure compared to surrendering it to the noisy neighbours of Manchester City.
United went into shock last spring. An engagement for Harry Gregg's testimonial in Belfast, two days after City had snatched their first English title for 44 years, dragged United's staff and players from their trance. But this was no ordinary handing over of a trophy. It settled on Alex Ferguson's empire as a form of grief.
For the 26 years of Ferguson's reign, the "repel all boarders" philosophy has held firm. Blackburn Rovers were the first to be smashed back into the water after their lone title win in 1995. Next to be knocked back overboard were Wenger's early Arsenal teams and the 'Invincibles' of 2004. Then Ferguson's gaze was turned on Roman Abramovich's Chelski mission: the first of his two big battles with obscene individual wealth.
City's invasion was far more painful. It flooded every street and alleyway in Manchester. It was high on the billboards and way down in the soul. The United clan could not take two steps across their city without running into a blue enemy. United had always set their sights on world domination. Now they could not control their own backyard.
The manner of the succession might have been designed to torture the United half of town. On the most dramatic final day in Premier League history, Ferguson's men were champions for 13 seconds at Sunderland until Sergio Aguero's late winner for City against Queens Park Rangers blew the roof off their Etihad Stadium.
Sunderland fans gloated by performing the Poznan: City's adopted, back-turning jig. A vision of hell was now reality for United's players as they mourned with their own 2,600 fans. The astounding wealth of absentee Abu Dhabi royalty had counted for more than 26 years of brilliant management and continuity. Red was no longer Manchester's defining colour.
And for us neutrals, one of the world's great metropolitan rivalries was now entertainment gold. Manchester was up there with Buenos Aires and Milan.
This is the backdrop to Sunday's City-United fixture on Sheikh Mansour bin Zayed al Nahyan's home ground. While a new arms race of youth cultivation and infrastructure investment gathers pace behind the scenes, it falls to 22 players to strike a blow in a title race that is demonstrably a two-club contest. Abramovich has destabilised Chelsea to the point of impotence and no one could fancy Spurs to knock off the big northern two from 10 points back.
The relationship is now beautifully poised. United have fallen behind countless times this term but lead the race by three points. Roberto Mancini's City could not even make the Europa League from their Champions League group and are now fully focused on retaining their Premier League title at United's expense.
One thing we know is that it would rank as Ferguson's greatest comeback to silence neighbours who were better known for wakes than celebrations until the glories of 1968 came raging back.
From 1998, when Wenger won his first title, to 2010, when Ancelotti's Chelsea prevailed, Ferguson was helped by Abramovich's volatility and Arsenal's loss of momentum post-2005. The manager commemorated by an Old Trafford stand and statue inspired all those comebacks but there were small measures of outside help from both London clubs.
This time, there will be no weakening at City, unless internal divisions or personality clashes run out of control. If Mancini were to lose his job, his replacement would surely come from the top five of European coaches.
Though the Sheikh is unlikely to spend much on reinforcements next month, he will not be doing a Randy Lerner and scaling back on his investment. Ferguson is fond of telling United fans and players: "We'd better get used to this, because City are not going away." They thought the same about Chelsea but have been helped by the owner's meddling.
Now, City's breath is forever on their necks. They can see tracts of the metropolis disappearing into the Etihad Campus. The old 'Beckham Belt' of Cheshire mansions is no longer solely United territory. The two sides pass each other uneasily in restaurants and upscale shops.
The pressure, in other words, is inescapable. And United know they must not lose Sunday's collision. Great comfort can be taken from the knowledge that Robin van Persie chose them ahead of City when he resolved to leave Arsenal. The Dutchman's majesty around the opposition's penalty box has transformed United's prospects.
Each side have six months of this stress to deal with. United are the "boarders" now, City the ones "repelling". Ferguson wants the pain of May avenged. (© Daily Telegraph, London)