When Robin van Persie walks out onto the pitch at the Etihad for his first Manchester derby this Sunday, he will of course catch a glimpse of what might have been this season. Instead of the red of United, he could just as easily have been wearing the blue of City. Alas, it wasn't to be.
Sir Alex Ferguson "never thought [United] could get van Persie." Arsenal were hopeful of persuading their striker, then in the midst of a remarkable season in which he scored 44 goals in all competitions, to stay at the club.
And if they weren't to convince him then it was almost taken for granted that he'd follow the money as his former teammates Gael Clichy, Kolo Toure and Samir Nasri did to City, the Premier League champions. But van Persie, to the consternation of some, joined United.
Why the surprise? Well, few thought that Arsenal would sell their best player to a club that, for much of the last decade, had been their biggest rivals.
While they got a good deal - $33m for a 29-year-old - which led Ferguson to claim that Arsene Wenger "could run a poker school in Govan", United had seen an inquiry for Nasri refused a year earlier apparently on the basis that they were rivals.
Wouldn't Arsenal have also got more money from the deeper-pocketed City or preferred that van Persie instead go abroad to Juventus where he could do them no harm? In truth, there wasn't really much they could do when the player had his heart so set on United.
"Manchester United breathe football in every aspect, for me it was quite soon that I made my decision," van Persie revealed. "It was based on a lot of things and all those things went to Manchester United. When you have to make a hard decision in your life I always listen to the little boy inside me. What does he want? That little boy was screaming for Manchester United."
It was a real coup for Ferguson. For he weakened one rival and frustrated another, thwarting City's plans to strengthen even further. "For this question, speak to the man in charge," City boss Roberto Mancini said when he was asked about van Persie.
He blamed the club's then football administrator Brian Marwood for not getting the deal done. But he needn't have because there's an inconvenient truth behind van Persie's decision to join United in favor of City.
It reminds us that for all the money the nouveau riche have, the traditional powers with their illustrious histories of success through the ages, at least for now and the near future, continue to exude an allure and appeal to those players with a romantic outlook on the game.
To the wider public to say that you have played for United still has a greater resonance, than to say you have played for City. That may change with time, but one presumes this is what the "little boy inside" van Persie was screaming back in the summer.
By coming to Old Trafford, he also brought the kid out in Ferguson. He now believes that a 20th league championship for United is a more realistic possibility than before. "I think we were still capable of winning the title without Robin, but he gives us a sort of certainty for the future." Mancini senses it too. "Without van Persie, they had two yards in front of us," he said. "Now, it's five because of van Persie."
On the one hand, that sounds like a bit of an exaggeration. After all, the gap between United and City heading into Sunday's top of the table clash isn't that great. It's still only three points.
And yet, on the other, it could be argued that it's only because of van Persie that United are in contention at all. Without his 10 goals and four assists in the Premier League this season, they would be 19 points worse off and all the way down in 13th instead of first.
Mancini must look on with envy. For how he could use van Persie. "At the moment we're not scoring a lot of goals, as we did last year," Mancini said after Tuesday's 1-0 defeat to Borussia Dortmund.
He's not lying. City have scored 20 fewer than at this stage last season while United have found six more.
It was Ferguson's determination not to lose the title on goal difference again like he did last season that motivated his decision to sign van Persie. "I think that, in my experience, where we are at the moment," he said, "you need two strikers [like van Persie and Wayne Rooney] who are going to get you over 20 goals a season. If you get that, you definitely have a really good chance."
Only that chance is being undermined by the rate United are conceding goals, which from a certain perspective is cheapening the number van Persie is scoring.
While City's attack has produced nine fewer goals than United's this season, their much tighter defense means they actually still have a better goal difference.
But that should take the polish off United's performances rather than van Persie's.
"He's got maturity to his game, authority, timing and understanding of the game," Ferguson said. "He's a player that every time I gave team talks he was a problem for us because he kept popping up in different positions, sometimes on the right, sometimes dropping off, sometimes in the middle, so at least I've taken that problem away."
Of course it remains one for City and Mancini to contend with at the Etihad on Sunday. Van Persie certainly doesn't appear to have any regrets about not joining them this season. It's now up to City to prove that maybe he should.
