Sooner or later, the balance of football power will shift in Manchester, but despite City's FA Cup victory against Stoke, all the money in the world cannot buy the title-winning credentials that have been the bedrock of United's success in the Premier League this season.
For all the significance of ending their 35-year wait for a major trophy, City have really only done the easy part by winning the FA Cup.
When it comes to trophies, the FA Cup is merely the icing on the cake for clubs in the top four because the silverware that really matters comes with winning the Premier League and the Champions League.
Achieving success in those competitions is the next step for Manchester City. Sheikh Mansour bin Zayed al Nahyan, having pumped hundreds of millions of pounds into the club, will want to be winning those big trophies. But taking the next step is not about another lavish spending spree on five or six world-class players this summer.
That would obviously do City no harm, but would it take them closer to winning the league or Champions League next season? Probably not.
What Roberto Mancini's team need is the priceless qualities that have driven United to the club's 19th domestic title this season, but you cannot go out and buy team spirit and that winning bond that has typified United this year.
City have had chances to go top of the Premier League at times this season, but they faltered on each occasion. That was not because they lacked the players. City's players are as good as United's, but the advantage that Alex Ferguson's men have over their counterparts at Eastlands is their unity, integrated teamwork and peerless ability to dig results out.
When City fall behind in games, they tend to stay behind, but United have shown time and again their ability to fight back and emerge tight corners with something earned by a late goal or comeback.
They have a camaraderie which has been forged by Ferguson and, quite simply, they are a team. The resilience that won United the title is what City lack -- and they need to find it if they are to take the next step.
There are two possible reasons why United have emerged as champions this season. The first is that the others just haven't been good enough to stop them.
But the second -- and most likely -- is that they have the edge over their rivals in terms of being able to get results when things are not going their way. They have had some shockers away from home this season, more bad performances than I can ever remember, but they have come out of it all as champions.
United will know, however, that City are not going to go away and, eventually, their neighbours will close the gap and trigger the shifting of power in Manchester. But there is a huge difference between finishing in the top four and actually winning the league or Champions League.
To edge closer to those targets, the first thing Mancini must do this summer is find a centre-forward who is capable of scoring 20 goals a season -- regardless of what happens with Carlos Tevez,
Winning the Cup is great and it means everything to the City fans, but if the team are struggling to live up to expectations next season, they will soon be after the manager.
They want results quickly and Mancini knows that a Cup win is only the start. (© Daily Telegraph, London).