Top jockey Kieren Fallon will not be able to race in today's Epsom Derby after the Court of Appeal overturned an earlier ruling allowing him to take part.
Lord Justice Jackson and Lord Justice Elias reversed a decision made by a High Court judge yesterday not to grant an injunction preventing the three-time Derby winner from riding in the classic event.
The order was sought by Ibrahim Araci, the owner of Native Khan, to prevent Fallon riding a rival horse, Recital.
Mr Araci brought his action over claims that Fallon had broken a "promise" to ride Native Khan and argued that, under the terms of a retainer agreement, he should not be allowed to ride any other horse in the race.
Fallon denied breach of contract and said there had been an "innocent misunderstanding".
Mr Araci was said to be "thrilled" by today's decision to grant an injunction.
His lawyer, Mehmet Erdogan, said: "He's thrilled. He always trusted the British legal system, that's why as a foreigner he invested in this country.
"He believed that justice would never go wrong in the UK."
Mr Erdogan said that Fallon had "deliberately and cynically" breached a contract.
"Five days before the race, surprisingly and shockingly, he informed our client that he would not be running our client's horse, but riding a competitor's horse.
"That was breach of contract," he said.
He added that it was "unlikely" the jockey would ride a horse owned by Mr Araci in the future.
In his ruling, Lord Justice Jackson said the status of Fallon did not allow him to avoid the law.
"There is nothing special about the world of racing which entitles the major players to act in flagrant breach of contract," he said.
He described the injunction as a "grievous blow to the defendant (Fallon)" but said it was his own fault.
"The defendant has brought this present predicament by himself."
One of the reasons Lord Justice Jackson gave for overturning the decision by Mr Justice MacDuff, was that the possible payment of damages by Fallon would not provide an "adequate remedy" in lieu of an injunction.
In his judgment, the debate over the correct figure would have been complicated.
"It is not easy to speculate what would have been the outcome of a race if different jockeys had been riding different horses."
He added that "on the basis of the material presented to the court", there was a risk that Fallon could struggle to pay damages "if things go badly" in the process of generating a figure.
"The defendant might not be able to meet that judgment in full."
He said that the jockey would risk paying damages for two separate breaches of contract, both not riding Native Khan and riding a competitor.
The High Court ruling took into account that it would be difficult for the owners of Recital to find a replacement jockey of Fallon's stature at such a late stage.
But Lord Justice Jackson said it was "unrealistic" that urgent inquiries had not already been made to find an alternative.
"It should be noted that the claimant faced precisely the same problem earlier this week," he said.
He went on to describe the consideration of the impact on the betting public who had placed wagers on Recital as "not a good point" because there is always a chance of a jockey pulling out of a race through injury.
"When a member of the public bets on a horse, he or she is running a multitude of risks," he said.
The judge added that he would "unhesitatingly refuse an injunction" if it would mean the Derby would not take place, because it is a "major national event".
But he said that while the ruling was unfortunate, it "doesn't materially retract from the event as a whole".
Lord Justice Elias agreed with the decision to grant an injunction.