Crystal Ocean has suffered a career-ending leg injury during routine gallops at Newmarket.
The Sir Michael Stoute-trained five-year-old was cantering on Thursday as part of his preparation for either the Prix de l’Arc de Triomphe or the Champion Stakes at Ascot.
While it is hoped he will recover to enjoy a second career at stud, his racing days are over.
“He’s had to have two screws inserted into a cannon bone,” Peter Stanley, spokesman for owner Sir Evelyn de Rothschild, told the Press Association.
“He’s fine after surgery. He’s come through the operation and is up and about.
“At this stage the vet sees no problem at all in him heading to stud, but it is early days.”
Never out of the first three in a 17-race career, Crystal Ocean was involved in an epic battle for this year’s King George VI And Queen Elizabeth Stakes at Ascot, just losing out to Enable.
For a brief spell he was the highest-rated horse in the world and finally landed the Group One his consistent efforts deserved at Royal Ascot in the Prince of Wales’s Stakes.