Kieren Fallon will not ride Recital in this afternoon's Investec 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 premier Classic.
The order was sought by Ibrahim Araci, the owner of Native Khan, to prevent Fallon riding the Aidan O'Brien-trained Recital, bringing his action over claims that the jockey had broken a "promise" to ride Native Khan. He 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.
"Five days before the race, surprisingly and shockingly, he (Fallon) informed our client that he would not be running our client's horse, but riding a competitor's horse. That was breach of contract."
Pat Smullen is to take the ride on Recital after the Ballydoyle team confirmed he was on standby on Friday night.
"Kieren is obviously disappointed and very sorry not to be riding in the Derby this afternoon," said Fallon's solicitor Christopher Stewart-Moore. "He wishes the owner of Native Khan the very best of luck and hopes that Pat Smullen has a good ride on Recital too."
Native Khan's trainer Ed Dunlop told BBC Radio 5 Live: "I've stayed well out of it, it hasn't really been my decision, but a contract was signed in my office and therefore for the last three and a half weeks, I've presumed Kieren was riding my horse and was obviously surprised when he wasn't."