For drama, intensity and, most of all, because the two teams are now so evenly matched, City vs United games are becoming as much of a "must-watch".
Manchester City or United? Rooney hints jury out on Mancunian derby
That open-ended statement won't stop speculation about his future.
No, it was that the United striker let it be known he already has made a mental note of exactly where he will be on April 28, as if he had saved the date with a Post-it on his fridge.
The answer, of course, is Etihad Stadium.
The 163rd derby between the blue and red sides of Manchester at City's ground when spring will be in full bloom is sure to be one of the hottest tickets in world soccer this season.
How does one say "clasico" in Mancunian? For drama, intensity and, most of all, because the two teams are now so evenly matched, City vs United games are becoming as much of a "must-watch" as the historic Spanish rivalry between Real Madrid and Barcelona.
Unless they should meet first in the Europa League, which can only happen if both sides survive at least into the quarterfinals, then United's crosstown trip in April will be the rivals' fourth, and likely most important, encounter this season.
It may help answer the riddle that the previous three games, as sensational as they all were, together failed to: Is City unseating United as the Manchester team to beat? Or are the guile and experience of United manager Sir Alex Ferguson enough to keep City - the "noisy neighbor," as the 70-year-old has called them - and the petrodollars of its Abu Dhabi owner at bay, at least in the short term?
As Rooney noted, the April match will be the second-to-last fixture in the Premier League for both sides. If, as now, City and United are still separated then by little more than a whisker at the top of the league table, then that game will take on the aura of a possible title-decider. Small wonder, therefore, that Rooney was already looking so far ahead.
With the April game firmly in mind, Rooney said United's 3-2 defeat of City at the Etihad in the FA Cup third round on Sunday, "psychologically ... it can only be good for us."
Truth is both teams could read what they liked into Sunday's result.
United, rightly, could claim that only victory counts. Already ejected from the Champions League and from the League Cup, and coming off successive losses in the Premier League, United needed this more than City.
At the teams' last meeting in the league in October, City famously won 6-1, a humiliation Ferguson described as "the worst result in my history, ever." A repeat of that on Sunday, or something approaching it, would have quickened talk that Manchester's balance of power has shifted and that Ferguson either is losing his touch or that his management skills, alone, cannot compete against a rival rich enough to recruit almost any player it wants.
Had United lost, Ferguson's astounding decision to field 37-year-old Paul Scholes would have looked almost as desperate as asking his former stars David Beckham and Roy Keane, who were both watching, to suit up, too.
But because victors are always right, the 3-2 score saved Ferguson from looking as though he scraped the bottom of United's barrel in bringing Scholes out of retirement, although, really, that is exactly what this was. Had Ferguson hired a midfielder like Wesley Sneijder last summer, he may not have needed Scholes to fill holes left by injury and illness.
City, which now must say goodbye to the FA Cup that last May provided the club with its first trophy in 35 years, has yet to prove that its expensively assembled team has the mettle to win the Premier League, its priority, and stay ahead of United in what Ferguson famously calls "squeaky-bum time." The rivals' April game will be played in that make-or-break late-season period when pressure is most intense.
But City, particularly tireless Argentina striker Sergio Aguero, was a magnificent loser. At 3-0 and a man down, manager Roberto Mancini's men could have been swamped, as United's were in losing 6-1 in October after defender Jonny Evans was sent off. Instead, City made Mancini look like a genius for his bold decision to rejig his formation to compensate for the loss to a red card of captain Vincent Kompany. After goals from Aleksandar Kolarov and Aguero, City came agonizingly close to a draw that would have been a deserved reward for its hard work in the second half.
For City, that almost felt like victory.
"If we show the same attitude and strength in other games that we showed against United with only 10 men then, yes, we can win the league," said Mancini.
Still a big 'if', but one that looks increasingly realistic.
Stay tuned. Particularly on April 28.