Superstar filly Alpha Centauri has been retired after suffering a chipped fetlock in her shock defeat to Laurens in the Coolmore Fastnet Rock Matron Stakes at Leopardstown on Saturday.
The news emerged on Sunday afternoon, after the Jessica Harrington-trained filly had undergone a thorough examination at Fethard Equine Clinic.
Her defeat to Laurens ended a magnificent run of Group One wins for the daughter of Mastercraftsman, which began with the Irish 1,000 Guineas and took in the Coronation Stakes, Falmouth Stakes and Prix Jacques le Marois.
Alan Cooper, racing manager to owners the Niarchos family, told Press Association Sport: "Unfortunately the decision has been taken to retire Alpha Centauri on veterinary advice and on consultation with Jessie.
"She had a chip in her right front fetlock - which you could see her feeling in the closing stages yesterday.
"It's not a catastrophic injury and hopefully she can enjoy a successful career as a broodmare."
Remarkably, it was also confirmed on Sunday that Aidan O'Brien's QIPCO 2000 Guineas hero Saxon Warrior had been retired following a tendon injury sustained in the Irish Champion Stakes.
The Deep Impact colt narrowly came off second best in a titanic battle with his old rival Roaring Lion at Leopardstown on Saturday.
He emerged as a top-class colt when winning the Racing Post Trophy at Doncaster at the end of last season, before reappearing with his Classic success in May.
Sent off odds-on favourite for the Derby, he could only finish fourth and was then beaten in the Irish equivalent.
He ran much better when second in the Coral-Eclipse to Roaring Lion, but was then badly struck down by the virus which hit O'Brien's yard in the summer.
Down the field in the Juddmonte International on his first run back, a race also won by Roaring Lion, he improved markedly on that effort at the weekend, but was yet again behind John Gosden's colt.
O'Brien told RTE Racing: "He badly damaged a tendon in the race which was a pity and when he came home last night we wrapped him up.
"When we looked at him this morning his tendon wasn't in a good place. There's a tear in there and it's a big pity.
"He was an amazing horse. Coming into this year we thought he was a horse with a chance to win the Triple Crown.
"When he won the Guineas, Donnacha (O'Brien) was of the opinion that he was a very fast horse, but we wanted to give him a chance in the Derby. We went to Epsom, but I felt he didn't act on the track.
"The lads then wanted him to run at the Curragh (Irish Derby), after that we decided to bring him back to a mile and a quarter, which we did do, but only seven days after the Curragh at Sandown and he was just chinned.
"Then he got very sick and the plan was to bring him back for three races, he was just ready to start back at York and we wanted to run him yesterday and then back at a mile at Ascot.
"It's probably my fault, I probably should have kept him at a mile."