Colleague who became Ferguson's adversary

United in crisis: How disagreement with formidable Irish horseracing magnate over Rock of Gibraltar soured relationship with Old Trafford manager

It is not slave's work to identify the similarities between Sir Alex Ferguson and John Magnier. Both have emerged from less than promising origins to mastery of their trades. Both are ruthless in pursuit of their aims. It is all in the nicknames. In Ireland, Magnier, the chief of the all-consuming Coolmore Stud empire, is known as "The Boss". A biography of Ferguson possessed the same title.

It is therefore also easy to see why the two men were attracted to each other, a relationship which was first embodied by the sharing of a promising 2001 two-year-old called Rock Of Gibraltar. However, only opposites, you might say, attract permanently.

A further Irish racing colossus, JP McManus, is nominally a part of the current tremors at Manchester United as part of the Cubic Expression company. Yet it is really down to Magnier because the transfer questions at Old Trafford all really stem from Rock Of Gibraltar.

There are detailed allegations to answer about the recruitment of players at the Premiership club, but the central issue is more simple. Ferguson never signed a contract concerning the ownership of Rock Of Gibraltar, but his own contract is now threatened over his interpretation of a verbal agreement.

The manager believes himself entitled to half the Rock's stud earnings, which, potentially, could be close to £100m. Even Coolmore, maybe especially Coolmore, get their fair share of duds when buying expensive yearlings at the world's bloodstock markets. The rare good stallions pay for the underachievers, which is why Magnier is loath to dilute the earnings of the Rock. Magnier may be worth around £200m, but he did not achieve that figure by giving it away.

This briefs' benefit is likely to be heard in early 2006 and Ferguson will be aware of the severity of the task. The case will be heard in Ireland and could be as tough as any away match he has faced.

Ferguson has been at Old Trafford since 1986 and is the longest-serving manager in the Premiership. Until recently it appeared only lightning could remove him. But then Magnier is probably more powerful than that. Pitchside cameras inform us that Ferguson likes chewing. But he has probably bitten off too much this time.

So who is this man John Magnier, who now owns more than a quarter of the most famous football brand in the world? He looks intimidating, even though he stoops from his 6ft-plus height, yet he is supposedly shy.

When the weather is cooler, a fedora adorns his head. In warmer times, dark sunglasses are apparently stapled to his forehead. Their location is surprising because you might imagine Magnier hiding behind his shades.

For while he might be the king of the jungle, Magnier prefers to spend his time in the loftiest of treehouses, away from the public gaze. He buys more $5m yearlings than he gives interviews and if you ever get to meet the great man there is more than a sense that he is uncomfortable with alien company.

Born in County Cork, Magnier left school at 16 to assist on the family stud farm after the death of his father. In the early heady days of Coolmore and Ballydoyle - the training arm of the operation - in the 1970s, he appeared little more than an apparatchik working for the yard's money man, Robert Sangster, and the legendary trainer Vincent O'Brien. The latter was his father-in-law and it was easy to imagine that Magnier was just trading on the great man's name.

That, however, was just base camp. The trio put the Coolmore and Ballydoyle axis on the map with a three-pronged system: to purchase well-bred yearlings at the world's finest sales; to train them expertly in County Tipperary; and then to sell their services as stallions. It was not a complex strategy but, like all good ones, it had never been thought of before.

Along the way Magnier has benefited greatly from a stud-farm tax concession granted by Charles Haughey, the former Irish Prime Minister. It is not a topic he considers worthy of discussion.

Soon Magnier was part of the domestic élite, hooking up with McManus and the financier Dermot Desmond, part of a group which was to become known as "the Irish mafia". Thus his horizons stretched beyond horses to international currency exchange and to interests in under-valued businesses. Manchester United fitted that criterion.

For a while it was all so beautiful. Ferguson was to be found at the head of Rock Of Gibraltar after yet another Group One success, allowing pleasure for the manager and a wider kudos for others behind the horse.

Now, as we approach a cup final of sorts, we will find out even more about the men in each dugout. We have already come to understand that Magnier is a man who holds grudges. He is a lordly figure who knows how to look after his lieutenants and staff, and has made others, as well as himself, wealthy on the great journey. His associates understand that being his friend is a good idea. Being his enemy is not a thought worth entertaining. Ferguson is beginning to learn that.