A generation of Manchester United fans have grown up knowing that their club is the biggest and most successful in the country, let alone the city. This is the generation that came of age during the era of the Premier League and blanket satellite television coverage. United finishing above City has been one of the great certainties of our footballing lives, like Richard Keys sitting next to Andy Gray in the Sky studio.

But then it seems that nothing is certain any more.

The Manchester derby is Saturday’s early kick-off in the Premier League but there are more than three points at stake. Since the billionaire investors behind Abu Dhabi United Group arrived at Eastlands in September 2008, each league or cup game between United and City has had a subtext to it that extends far beyond what happens in the ninety minutes.

Put simply, it is inevitable that City’s wealth will bring them a trophy sooner rather than later and quite probably a league finish above United too. Either event will cause United’s fans to further reassess their relationship with the team across town. The Old Trafford faithful are getting used to the fact that United’s neighbours have more money than them now, but any evidence of a shift in power on the pitch would be a lot harder to take.

Should City win a trophy this season (and they are still fighting on three fronts) then, for a start, the banner at Old Trafford that continues to taunt City for their lack of major silverware since 1976’s League Cup would have to come down. Finishing above United in the league this season, however, would arguably represent an even greater coup for Roberto Mancini’s side, whether or not it resulted in the Premier League title.

You have to go back 20 years to find the last time City bettered United’s final league position. In 1991, under player-manager Peter Reid, City finished fifth on 62 points with United three points worse off in sixth. Arsenal took the title that year but, while the identity of the champions might have been a familiar one (although the Gunners are enduring a six-year silverware drought of their own at present), a glance down that league table emphasises just how long ago it was when City fans last had bragging rights over United’s. Crystal Palace finished above both Manchester clubs in third, for example. Wimbledon and Luton, who both retained their First Division status in 1990/91, are no longer even in the Football League.

Comparing the stability of the Ferguson dynasty at Old Trafford with the turbulent quarter of a century that City have been through in the same period is a statistician’s dream. Back in 1991, Sir Alex Ferguson had been in charge at Old Trafford for four-and-a-half years but Peter Reid was already the fourth full-time City manager that he had been pitted against. Mancini is the tenth man to have filled that role since then. Ferguson has won twenty-four major honours with United, all but two of them since the one and only time United’s final league position was inferior to City’s on his watch. Since the Scot took over in November 1986, City’s only two trophies have been picked up as a result of their travails outside the top flight – and one of those was for winning promotion via the third tier’s play-offs in 1999.

Fast forward to this season, though, and a win for City at lunchtime on Saturday would elevate them to second place – before Arsenal play, at least – and put the Blues just two points behind United at the top of the table, albeit having played a game more. History might count against City winning at Old Trafford, given that they have only done that once since 1974, but Mancini’s side are a completely different proposition to the vast majority of City teams that have travelled to the Theatre of Dreams since the afternoon of Denis Law’s back heel. With United having finally lost their unbeaten record at Wolves last Saturday, after threatening to do so at West Brom and Blackpool already in 2011, the teams chasing the league leaders sense weakness. A win this weekend, though, would put United back on course for that record-breaking nineteenth title.

The game will have an emotional dimension to it as well because it comes less than a week after the fifty-third anniversary of the Munich air disaster, which resulted in the deaths of 23 people including eight United players and three members of the club’s staff making their way back from a European Cup tie in Belgrade in 1958.

United’s manager called City “a small club with a small mentality” in 2009 when they celebrated Carlos Tévez’s move across the red-blue divide with a billboard welcoming the Argentine to Manchester. Ferguson’s point was that City were still measuring their success in terms of getting one over on their rivals, like an isolated derby win in the days when the two clubs usually found themselves in different halves of the table. For United, though, beating City suddenly has a lot more bearing on their season and the club’s standing than it has for a while. The successes last season over their resurgent rivals were a genuine gauge of United’s continued supremacy in the city, for the time being at least.

However, the ecstasy felt by United supporters at that hat-trick of dramatic derby wins during the last campaign was tempered by the knowledge that it had been very hard work. All three victories needed late goals. City were always going to come back stronger this term and they have done just that, flashing their cash again and rising into the Champions League spots. The question going in to Saturday, as with each passing fixture between the sides, is could this be the day when City start to outstrip United on the pitch as well as off it?

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You can back United at 4/5, City at 7/2 or the draw at 13/5