Popular mare Ouija Board has been retired by owner Lord Derby after an injury forced her out of her farewell race, Sunday's Hong Kong Vase.
The five-year-old was found to have a sore leg during a routine examination and was scratched from the race by trainer Ed Dunlop.
"It is a very sad end to her career and emotional for everyone," said Dunlop.
"Much to our surprise the mare wasn't right. The damage was unremarkable but we decided that enough was enough."
Ouija Board became the most successful horse in the history of the Breeders' Cup when she won the Filly & Mare Turf for the second time in three years.
That race in November capped a magnificent 2006 for Ouija Board, who also triumphed in the Prince of Wales's Stakes at Royal Ascot and the Nassau Stakes at Glorious Goodwood.
She had been set for a showcase swansong in Hong Kong with Frankie Dettori on board before injury struck.
"She has jarred herself either on the dirt or the grass," explained Dunlop.
"I was with Lord Derby, my own vet and the Hong Kong vets and we all agreed it was the right decision."
The untimely injury means Ouija's final race was her third-place finish behind Deep Impact at the Japan Cup.
The seven-time Group One winner will now be retired to stud.