Cheltenham Gold Cup winner Denman has died at the age of 18, champion trainer Paul Nicholls has said.
Denman won the 2008 Gold Cup, beating previous winner and rival Kauto Star by seven lengths, and retired in 2011.
The decision to put him down was taken by owner Paul Barber with the support of Nicholls, head lad Clifford Baker and vet Buffy Shirley-Beavan.
“We all agreed it was the right thing to do because but he has gone downhill in the past few days,” Nicholls said.
“We did not want to see him suffer.”
Welsh jockey Sam Thomas rode Denham – nicknamed the Tank – to his 2008 Cheltenham highlight while the Nicholls-trained horse also landed the 2007 Lexus and the Hennessy Gold Cup in both 2007 and 2009.
He initially enjoyed success in novice hurdles but only really marked himself as a real star when he switched to fences and defeated his rivals by 10 lengths and more in the Royal & SunAlliance Chase at the 2007 Cheltenham Festival.
Later that year Denman took an easy win under top weight in the Hennessy at Newbury before going on to claim the Lexus Chase.
A Cheltenham Gold Cup showdown with stablemate and reigning champion Kauto Star soon followed and Denman galloped to glory by seven lengths under Sam Thomas.
He was heavily backed to repeat that triumph the following year, but Kauto Star got his revenge.
Nicholls’ charge turned in a truly memorable weight-carrying performance to win a second Hennessy in 2009, competing off a 13lb higher mark than in 2007 and giving nearly a stone and more to each of his rivals.
That was to be Denman’s final victory, although he chased home Imperial Commander to finish second in the 2010 Gold Cup and filled the same position behind Long Run in 2011.
BBC racing correspondent Cornelius Lysaght
During a golden era for steeple chasers, Denman was one of the greats, enjoying a high-profile rivalry with another of them, Kauto Star, who was his neighbour in the stables of their trainer Paul Nicholls.,
Fans wore rosettes – were you for Denman or Kauto? – before their showdown in the 2008 Gold Cup, and there was much debate about which was the more popular. I always thought that people admired Kauto Star but they loved Denman, not least when he came back from a serious heart problem.
Regardless of Cheltenham, the topweight-carrying performances in two Hennessy Gold Cups wins by ‘the Tank’ rate as two of jump racing’s most magnificent in modern times.