Thomas Chippendale lost his life at Royal Ascot on Saturday when he won the Hardwicke Stakes for trainer Lady Cecil and jockey Johnny Murtagh.
The four-year-old colt collapsed and died of a suspected heart attack after passing the line in a dramatic, and deeply sombre, renewal of the Group Two over a mile and a half.
Murtagh said: "He ran his heart out and was pulled up at the line.
"He lost his balance and I don't know what happened to him.
"It's heartbreaking for everyone involved - it should have been a great win.
"It's just devastating the way it's finished."
The 9-4 favourite, Ektihaam, also slipped up on the bend and gave Paul Hanagan a nasty fall, but both the former champion jockey and the horse were reportedly unscathed.
Hanagan set off to make all of the running - tactics he had employed last time out when beating Thomas Chippendale by six lengths.
Universal took up the running following Ektihaam's departure and had a good break on the field, but the challengers were stacking up two furlongs out.
Murtagh kicked for home well over a furlong out, but Frankie Dettori, still searching a first win of the week, got a great tune out of Dandino.
He could not sustain his challenge, however, and went down by a length to the 8-1 scorer, with Universal another two and a half lengths back in third.
Luca Cumani's Mount Athos and the supplemented Sir John Hawkwood never threatened to get involved.
While Hanagan walked away he was stood down for the rest of the day.
Lady Cecil said: "I'm heartbroken, it was devastating, but at least it was quick and he wouldn't have felt anything.
"I didn't know what had happened until I came back. I thought everything was all right but it seemed all quiet and I had no idea why.
"The horse had been working so well."
Owner Sir Robert Ogden's racing manager Barry Simpson said: "He was such a consistent horse, his form was in the book although I was disappointed when he was beaten by Al Kazeem but that horse has won two big races since."
Dandino's trainer Marco Botti said: "It was a very messy race and he got hampered when the other horse fell and by the loose horse.
"He finished the race very well and we will continue preparing him for the Caulfield Cup and the Melbourne Cup."
Mark Johnston, trainer of Universal, said: "It was unsatisfactory. The jockeys didn't know whether to go with the loose horse or not.
"It hasn't suited us but he stayed on well when the fourth horse (Noble Mission) went past him.
"He's in the King George and that would be tempting, while races like the Canadian International, Japan Cup and the Irish Leger will also be considered."