Manchester United and Manchester City have to act against their reputations being so cheapened by the puerile behaviour of Gary Neville and Carlos Tevez.
It is their problem and one that in the current climate in the city requires a swift response.
If the Football Association decides to respond to the provocation which so inflamed the equally brainless fringes of the supporters of both clubs they should be representing a second wave of discipline aimed at enforcing general standards of behaviour among players operating in the world's best-paid football league.
First, though, United and City must make it clear what they expect of their players at a time when their historic rivalry is clearly heading for new levels of intensity on the field and potential viciousness off it.
What that conduct can never be is the kind of self-regard and indulgence which has become a staple of Tevez's more successful performances or the dismaying tendency of the 35-year-old Gary Neville to revert to the behaviour of a malignantly points-scoring adolescent.
Both should be told by their clubs that they have passed, in Neville's case long passed, the time when they can continue to respond so instantly to the promptings of the worst aspects of their nature.
In Neville's case the problem is plainly terminal. A brilliant career – one which persuaded Sir Bobby Charlton, for whom Wednesday's pettiness was particularly appalling, to select him as the right-back of United's post-war years – has long been sullied by mindless acts of provocation, especially against Liverpool supporters.
Perhaps with the decline of his powers, Neville feels some kind of extra need to make his presence felt. He should know the desire has never been more counter-productive. Rabble-rousing is a poor substitute for leadership. Some may say he wears his Manchester United heart on his sleeve but in the case of someone who should by now have acquired some of the statesmanship of his club-mate Ryan Giggs, the result is a dishevelled substitute for genuine passion.
Tevez is simply wearisome in his gallery-playing, a tendency which became rampant from the moment it appeared Sir Alex Ferguson was unwilling to meet the valuation of the player's owner-agent. Ferguson never said Tevez wasn't a player of considerable value, simply that at £30m-plus his price was rather too strong for his taste.
Yesterday Tevez, far from drawing back from his excessive celebrations of Wednesday night, compounded the problem with another ferocious attack on Neville on a Spanish radio station. He talked about Neville being a creep, and worse, which is of course a matter of opinion, but it is one that comes less than impressively from someone as hell-bent as himself on milking moments of success.
His self-portrayal as a warrior devoted first to the United fans, now to his new ones at Eastlands, was beginning to wear thin after the first few performances at Old Trafford. Now it is so much part of his demeanour that the effect is rarely less than nauseating.
No one was entitled to sneer at the levels of effort he produced on behalf of United – nor to question his current value to his new club, with an impressive burst of 17 goals in all competitions.
That latter achievement is of course the acceptable way of determining his proper value in the market place. Certainly there is no question that Tevez is an admirably good-hearted player but it is a quality less than brilliantly served by his constant self-advertising.
His value is best arrived at by the manager who most desires his services. Certainly it is hard to imagine a football man as sophisticated as his new boss, Roberto Mancini, will be prepared to put up indefinitely with what appears to be a constant need to remind the world, and especially Manchester United, that his departure from Old Trafford was some kind of terrible injustice.
It wasn't. It was the result of a manager's right to pay not a shilling more than what he considered a proper price.
In both cases, Mancini and Ferguson appear to have a clear obligation. It is to tell Tevez and Neville that it is time they grew up. Both are playing a silly game. But it is also a dangerous one.