Cheltenham Gold Cup day was overshadowed after Sir Erec suffered a fatal injury during the opening race of the day.
The 11/10 favourite had problems before the 1.30pm Triumph Hurdle, needing his shoe to be repaired which caused a brief delay to the start of the race.
And then he tragically suffered the awful injury between fences before news filtered through at Prestbury Park that the horse had to be put down.
Nico de Boinville was on board winning 20/1 outsider Pentland Hills.
But the jockey muted his celebrations and reserved his thoughts for Sir Erec.
In a brief but classy statement, de Boinville said: “My thoughts are with those involved with Sir Erec.
“I never like to win a race when something like that’s happened in it. But sadly that’s the reality of the sport."
Speaking on ITV Racing, former champion jockey Sir AP McCoy added: "I’m absolutely heartbroken for Sir Erec. That is the toughest thing about this sport."
ITV broke the devastating news to millions of viewers watching on at home in the UK.
And in a statement on Twitter , the broadcaster passed on its condolences to trainer Joseph O’Brien.
“The devastating news we all feared has unfortunately been confirmed,” said ITV.
“Following his injury in the JCB Triumph Hurdle Sir Erec has been put down.
“The ITV Racing team extend our heartfelt condolences to @JosephOBrien2 & everyone associated with this wonderful horse.”
Sir Erec’s demise was sadly the second fatal incident during this week’s Festival.
On day one, another favourite in 9/4 shot Ballyward perished in the National Hunt Challenge Cup.
Cheltenham organisers released a statement amid pressure from Animal Aid group condemning the sport.
It read: “Sadly Ballyward sustained an injury in the National Hunt Chase.
"He was immediately attended to by our vet team, who very sadly determined that it was necessary to euthanize him on welfare grounds.
"As animal lovers, we hate to lose any horse and of course we shall review this incident. Our thoughts are with the Ballyward’s connections."
For all the latest on Cheltenham Gold Cup Day, go to our live blog HERE .