Man City: City supporters have been forced to vacate the moral high ground but, writes United fan Andy Mitten, they believe it is a price worth paying

I didn't get to sleep for three hours last night," e-mailed a Manchester City supporting friend on Tuesday. "I've never known a day like it. I couldn't stop thinking about our team with Robinho.

"It looked like we'd get Berbatov for a while, but then I remembered a golden rule of football. Never underestimate Manchester United."

Other City fans were less considered and revelled in talk of football's marquee names joining their club in the January transfer window. Then Noel Gallagher, the self-styled one-man crime wave no Mancunian had ever heard of before Oasis, opined that he: "likes the fact United fans will be giving money to City every time they pay for petrol."

By Wednesday, the giddiness of the social inadequates who hang around empty football grounds on weekdays increased. One City fan, whose attempt at Arab headwear (in appreciation of their new owners from Abu Dhabi) appeared to be a pair of white knickers and red electricians' tape, boasted how City would be buying Cristiano Ronaldo in January.

You can easily mock, but Sir Alex Ferguson, having outmanoeuvred Real Madrid, now finds that the much-maligned club on his doorstep, a club who have hired and fired 14 managers since he took over in 1986, can claim to be the richest in the world.

United's domination under the Govan great has twice been tested by a suddenly enriched rival. And both times there was a temporary shift in power, first Blackburn in the mid 1990s and more recently Chelsea.

City fans have enjoyed this week, but what does it mean for the Manchester rivalry? On one level, not much. United may be domestic and European champions, but City won both Manchester derbies last season.

Unlike other derbies, Mancunian enmity has its roots not in social and economic inequality, but purely in football. Both sides have laid claim to the status of top club in Manchester. Before the war, City had been the more successful; United's first league and cup victories were achieved, according to City fans, through subterfuge when United poached their best players for a pittance.

And the list of United's crimes against their neighbours went on from there. United fans, meanwhile, gloried in their club's far greater glamour and worldwide fame.

Like Glasgow, Manchester is a football city. Rain, a rich industrial and musical history (the Gallagher brothers are City, as are Doves and Badly Drawn Boy. Ian Brown and Mani of Stone Roses fame are Reds, ditto New Order's Peter Hook) are forever entwined with its image, but it is football which defines Manchester.

Glasgow, Milan, Munich and Madrid come close, but with United averaging 76,000 and City 41,000, more people watch the Manchester clubs than the big two in any other European city.

In other cities, though, the playing rivalry is more equal. Celtic, Rangers, Internazionale or Atletico Madrid have all recently garnered silverware. City have not won a major trophy since 1976 - a fact celebrated by an ever-increasing odometer hung from the Stretford End.

Without trophies to back up any claims of supremacy, City stress their authenticity as the Manchester club in contrast to United's near global reach. Their fans are cast as down to earth, humble Mancunians who sneer at those dirty RAGs (Red Arrogant Gets) from Trafford (since the 1974 creation of Metropolitan boroughs, United's ground sits outside the City of Manchester boundary) who only started watching United when they won the 1999 treble.

For their part, United fans claim that City fans don't need a passport because their team never plays abroad. They've heard so many new City signing refer to the club as "massive" that they've hijacked the phrase in mockery.

The terms "bitter blue", "obsessed" and "liars" are frequently used. Robinho didn't go for the "massive" line - he just called City "Chelsea" before realising his slip.

Official City flags also boast of the club's Mancunian identity, reading "This Is Our City" and "The Mancunian Way".

A 2007 advertising campaign, which saw the same slogans appear on billboards and buses in greater Manchester, experienced high levels of graffiti, with red paint bearing the legend "31 years".

The campaign struck a chord with City's support as flags with statements like: "Welcome to Manchester" and "Madchester City" greet United fans.

The geographical argument is subjective and contentious. The key findings of a report by Dr Adam Brown of the Manchester Metropolitan University revealed the following two statistics which seemed to pacify both fans, namely that Manchester United have more season ticket holders with an M postcode, while City have a higher percentage of season tickets with the same letter. As a rough guide, United have more support in the west and north of the Manchester urban area, while City enjoy strong support in Tameside to the east and in south Manchester.

It amused United fans that while they objected to the Glazer takeover - partly because the club is now buried in £600m of debt, City fans welcomed the disgraced former Thai president Thaksin Shinawatra a year ago, just as they're celebrating their new owners from the Abu Dhabi United Group.

"I am not fussed who bankrolls our club if it means we can attract some decent players and get to watch some good football," says fan Wayne Barker.

And that's the crux. For some City fans it's success at all costs, even if it means abandoning the moral high ground and their identity.

Perhaps they are more like their red neighbours than they would like to admit?