Classic winner Covert Love has been retired after suffering a strained ligament.
The Azamour filly gave trainer Hugo Palmer his first Classic success when winning the Darley Irish Oaks at the Curragh last year, and added a further Group One victory in the Prix de l'Opera at Longchamp.
Also second in the Yorkshire Oaks, she had been due to make her four-year-old debut at Royal Ascot in the Prince of Wales's Stakes.
Palmer told Press Association Sport: "Very sadly we have had to retire Covert Love, which is a great shame.
"She has a strained ligament, which is the sort of thing with a gelding, whose only value is on the racecourse, in a year's time there'd be a chance to race again, but obviously with a Classic-winning filly it's a different ball game.
"It's obviously disappointing for her owners, who were looking forward to Royal Ascot and the season beyond, for Glen Magee, who rides her at home, and for all the team.
"But we are proud of what she achieved last year, she is so game and so giving. As one of her owners said, there's a line from Casablanca - we'll always have Paris."
He added: "She gave us some special days last year and we will miss her hugely, but she owes us absolutely nothing. She doesn't know there's anything wrong with her, she's only very fractionally lame at the trot, but we would be unduly risking her.
"It came to light (on Sunday morning) with a swollen joint and is a stark reminder of why the big days are so special.
"The Curragh was absolutely magical - one of the great privileges of my profession is to train a nice horse for nice people. Not everyone in the syndicate knew each other but became close and we had a wonderful journey.
"We went to the Curragh having won a Listed race, hoping to be in the first three, but she won by three lengths. She was then just nudged off at York, before Paris, which is a day I'll never forget.
"The saddest thing is she is a big, rangy filly and what she achieved at three was fairly remarkable - she looked and seemed so much better at four."