FEW footballers polarise opinion quite like Roy Keane. Depending on your point of view, the former Manchester United star is either a tortured genius or a thuggish brute - either way, he is one of the greatest midfielders the English game has ever seen.

During 12-and-a-half years at Old Trafford, Keane was the heartbeat of a Manchester United side that swept all before them.

As a midfielder, the Irishman combined skill and a steely determination to steer the Red Devils to seven league titles, but it was as a captain that his influence was most keenly felt.

Few figures have ever commanded the same authority and influence as Keane. His tremendous desire and ferocious will to win made him the playing embodiment of his manager.

While Sir Alex Ferguson barked instructions from the sidelines, his skipper made sure they were enforced on the pitch. The pair's relationship was as close as any in the game.

Keane demanded that his team-mates gave their all for his manager, Ferguson defended his captain whenever he over-stepped the mark. While other Manchester United players were jettisoned for relatively minor mistakes, Keane survived his indiscretions.

Arrested after a scuffle in a bar, admonished after admitting to targeting Alf Inge Haaland, accused of being unable to control his temperament and absolved despite criticising his own fans - whenever the 34-year-old erred, Ferguson was always there to dig him out of a hole. All he asked in return was loyalty. An old-fashioned concept, but one that Ferguson continues to cherish above all others.

For more than 12 years, he got it but, earlier this month, Keane made the mistake that was to prove terminal to his Manchester United career.

Furious after his side's abject display at Middlesbrough, the injured midfielder launched a series of personal attacks in an interview for MUTV. Rio Ferdinand, Alan Smith, Darren Fletcher and Liam Miller were all singled out for abuse - in a club that prides itself on its unity, Keane had ripped the dressing room apart.

Ferguson probably agreed with much of his captain's sentiment. Secretly, he no doubt admired his searing honesty and heartfelt disgust. But, crucially, he deplored the Irishman's willingness to berate his team-mates in public.

From that point on, it was no longer a matter of if Keane went, it was simply a question of when.

Most people expected a parting of the ways in May but, by stripping the midfielder of the captain's armband, Ferguson must have known that he was making an insult Keane simply could not accept.

His dealings would have made him expect a violent reaction. While the rest of the country was stunned by yesterday's events, they probably came as no surprise to Ferguson.

The Manchester United manager has lost a world-class midfielder and his most trusted lieutenant. But at the same time he has reasserted his authority and removed a festering sore that threatened to overshadow the rest of the season.Football has lost one of its most volatile love affairs.

By the end of his time at Manchester United, even Ferguson had come to realise that there are two sides to Roy Keane.