THERE is a passage in Roy Keane's book that seems particularly apposite this morning.

Almost exactly a year ago, Keane was sent off after a contretemps with Alan Shearer at the fag-end of a thrilling encounter that went Newcastle United's way by the odd goal in seven.

In his autobiography, Keane recalls how he was being wound up by Shearer immediately before he struck the Newcastle captain to earn himself a red card.

The tale Keane told contained several vulgar words, but basically he wrote: "Shearer was calling me an idiot. He was right. To do what I did, I must have been an idiot."

Fast forward to Saturday, and Jason McAteer showed just what a great big idiot - Keane used a rather more rude word, shall we say - the combustible Manchester United midfielder remains.

Yes, McAteer should have been booked for wrestling and ultimately hacking at Keane to leave his erstwhile international teammate on the floor.

And to be honest, David Beckham - that epitome of respectability and now father of two - was fortunate not to have had first use of the bathwater in the United dressing room after a handful of ill-advised lunges after he had been booked.

But Sir Alex Ferguson must be a bigger "idiot" than even his fiercest critics would claim if he absolves his captain of blame for Saturday's brainstorm.

Keane is supposed to be a mature individual; a talismanic leader of United, and until the summer the Republic of Ireland.

Yet with one wild swing of his forearm, Keane left himself open to the charge of crass footballing stupidity.

A four-game ban will be the result of his admission that he tried to hurt Alfie Haaland in the Manchester derby in April last year; his assault on McAteer will bring an automatic three-match suspension.

But why, at the age of 31, is Keane still acting like the playground bully, using violence to settle scores?

Ultimately, it must come down to Keane's relationship with his manager.

He is closing in on a dozen sendings off, yet Ferguson continues to countenance his skipper's hair-trigger temperament.

From stamping on Gareth Southgate in the 1995 FA Cup semi-final replay, all the way through to his "idiotic" slapping of Shearer, Keane's CV is littered with evidence of his failure to learn his lessons.

And so on Saturday, when a player with a semblance of sense would have turned the other cheek, it was McAteer's left cheek that felt the full force of Keane's elbow.

Just as a Test match batsman susceptible to short-pitched bowling can expect a barrage of bouncers, so Keane will now be the target of verbals and even a little roughing up.

Patrick Vieira has grown up; Beckham patently has not, as his reaction to being booked at the Stadium of Light proved.

And neither has Keane, the man whose seven-game break from league action could have a cataclysmic impact on United's title hopes.

Keane is the driving force behind the Old Trafford machine. And if you doubt his true importance to United, consider this.

United have missed out on the Premiership three times: last season, in l995 - when Eric Cantona was banned for the denouement - and in 1998, when Keane's cruciate knee injury saw him miss all but the first month of the campaign. So, for as long as Nicky Butt remains sidelined, and Juan Sebastian Veron has a peripheral influence on United, Keane is an irreplaceable cog in the United wheel.

As he reflects on his folly during his forthcoming month or two of enforced inactivity - starting with the explosive trip to Leeds United on September 14 - perhaps Keane might finally give his violent side the elbow.

Either that, or start on a new book