NEWMARKET, England — John Magnier and Sheik Mohammed dominate the European circuit but have little in common including, at the moment, mutual respect.

Magnier, 58, is the intensely private cattle farmer’s son who left school at 15 to run the family farm. He transformed the Coolmore Stud in Ireland into the most successful operation in Europe.

That he is said to be worldwide racing and breeding’s most influential man, ahead of Sheik Mohammed, is some achievement.

The Sheik, 57, prime minister and vice-president of the United Arab Emirates and ruler of Dubai, was born into riches. An impulsive statesman and sportsman, he has poured billions into building the Godolphin racing empire to challenge for the biggest global prizes.

But, despite seemingly limitless resources, he has been unable to match the Coolmore Stud’s success. Magnier, with two Derby winners, Galileo and High Chaparral, this century has been able to restock his wealth-creating stud with new champions such as Montjeu to replace ageing money-spinners like Sadler’s Wells.

While much of the success achieved by Magnier, son in-law of legendary trainer Vincent O’Brien, is home-grown, Sheik Mohammed still has to purchase much of his best stock.

That must gall a competitor such as the Sheik and, as the battle for supremacy has turned nasty, sparks could fly in the battle for fresh ammunition in Newmarket when both seek to re-stock with the most blue-blooded thoroughbreds.

One bloodstock circuit regular has not seen them exchange a word for more than a year and they are unlikely to feel any more cordial following the recent spat between Magnier’s main trainer, Aidan O’Brien, and the Sheik’s jockey, Frankie Dettori.

After last month’s Queen Elizabeth II Stakes at Ascot, Dettori accused his rivals of tactics aimed at ruining his chances, although O’Brien jockey Seamus Heffernan later won his appeal over the 14-day ban handed down by Ascot stewards. O’Brien said Dettori “had thrown his toys out of the pram” and “was paranoid about Coolmore horses and knew he had ridden a bad race”.

It was the latest in a year-long sequence of events which shows that the rivalry between the camps extends way beyond the track although Magnier, wearing a signature pale suede fedora, told Sports-mail yesterday: “We are not in a feud with anyone. Read my lips.”

For far too long, Magnier and his lieutenants have eschewed the progeny of the Sheik’s Darley stud. This one-way street eventually made the Sheik crack. He was also thought to be unamused that Dettori rode Scorpion for Magnier to win last year’s St Leger.

Dettori later expressed regret that he had worn Coolmore’s colours to win a Classic and he has not since ridden any O’Brien-trained horses.

What Dettori may not have known was that Magnier thanked Sheik Mohammed personally at the Keeneland sales for lending him his jockey. He believed the gesture was appreciated. Perhaps not.

Although far busier than before with his new responsibilities as Dubai’s ruler, Sheik Mohammed decided to shake off any financial constraints at last month’s Keeneland sales when he, new wife Princess Haya and principal bloodstock agent John Ferguson, vied with the Coolmore entourage.

The Sheik simply would not be beaten, buying one colt for around £4.5million and another for £4m. In 72 hours he spent almost £30m on 33 lots, compared to Coolmore’s £4.8m on 10, seven bred by themselves.

Apparently downcast, Magnier hid one central fact. Many of the Sheik’s purchases were part-owned by Coolmore through partnerships.

HOW THEY MATCH UP

o JOHN MAGNIER: Estimated to be worth £592m, his Coolmore Stud earns more than £140m a year. Aidan O’Brien trains the majority of his horses. No owner can match his 11 English Classic wins this decade.

o SHEIK MOHAMMED: Seemingly limitless wealth. Runs the Godolphin training outfit and has 1,000 horses in training worldwide. Owns the Darley Stud. Has only three English Classics to his name since 2000.