One of the closest professional relationships in English football is showing signs of serious strain following revelations of a heated training-ground bust-up between Manchester United captain Roy Keane and manager Alex Ferguson.

The row, which is understood to have taken place in full view of other players, occurred during United’s summer training camp in Portugal three weeks ago. Keane attacked the wisdom of Ferguson’s decision to allow players to be accompanied by their wives and children.

Keane is said to have remonstrated with his manager that a training camp should be precisely that and not a holiday, complaining that permitting family members to travel with the squad was unprofessional.

Ferguson disagreed, insisting that a camp so early in the pre-season period was as much about bonding and cementing team morale as serious fitness work.

Their fall-out has cast a shadow over the club’s preparations for the coming season and shed new light on why Keane is missing from the current four-match tour of Asia.

In an interview on Friday, fellow-Irishman John ’Shea confirmed that Keane had trained normally with the rest of the United squad in Manchester the day before they flew to Hong Kong for Saturday’s opening friendly match against a Select XI.

THE SUNDAY TELEGRAPH