Jonjo O'Neill's stable star Exotic Dancer died after suffering a heart attack following the totesport Bowl at Aintree today.
The nine-year-old finished second behind Madison Du Berlais in the Grade Two contest, beaten four and a half lengths in a race which also saw Denman fall at the second-last, but later collapsed upon his return to the stables.
Exotic Dancer, owned by Robert Ogden and one of the most consistent chasers of his generation, won eight of his 29 career starts, including the Grade One Lexus Chase at Leopardstown earlier this season.
He was also placed in two Cheltenham Gold Cups, having finished third to Kauto Star last month.
O'Neill said: "Half an hour after the race he was just walking along in the stables when he just lay down and that was it.
"He was very tired coming back in off the track.
"I said to Barry (Simpson, owner's racing manager) he looked like he had run his heart out, and he looked really tired.
"We took the saddle off him and he went back to the stables and was OK.
"We were leading him round and Hannah, who looks after him, felt he wasn't right so we took him down to the vets, where he laid down and that was it - there was nothing we could do.
"He was a great old horse and you need those sort of horses in the yard.
"Winning the Lexus Chase at Christmas was my favourite day with him.
"He'd be the best chaser I have trained."
Exotic Dancer accrued over £800,000 (€874,767) in prize money.
Despite his raw class, O'Neill's son of Turgeon was always left having to play the role of bridesmaid to the great Kauto Star, who consistently had his measure.
In addition to his Gold Cup reverse in March, Exotic Dancer finished second behind Paul Nicholls' nine-year-old in the 2006 King George VI Chase and the 2007 Betfair Chase at Haydock.
Ogden's gelding nonetheless pocketed five Graded triumphs within his eight-win haul.
Exotic Dancer jumped into prominence with a big-race handicap double at Cheltenham in 2006, claiming both the Paddy Power Gold Cup and the Boylesports.com Gold Cup.
Simpson said: "You feel for everyone and not just ourselves - it hits stable staff more than it hits the owners.
"It has just happened so quick. He came back in and didn't look quite right - he looked tired.
"It is a very, very sad end to a very, very good career for the horse.
"We bought him as a three-year-old and have kept him on the go.
"Even today, with the disappointment of not winning, we were making plans for next year, but sadly that is not going to happen.
"We will have to go and find another one just like him, or even a little bit better than him, but that won't be easy."