Replay - Totesport Bowl Chase
Exotic Dancer died after suffering a heart attack while Gold Cup star Denman fell chasing winner Madison Du Berlais in the Totesport Bowl Chase at Aintree.
The Jonjo O'Neill-trained Exotic Dancer finished second but suffered a fatal heart attack in the stables.
Denman, under Sam Thomas, was involved in a two-horse race with Madison du Berlais when he fell heavily two out.
The former Gold Cup winner suffered a bad cut, although he is expected to make a full recovery.
Exotic Dancer was one of the top staying chasers of recent years, winning the Grade One Lexus Chase at Leopardstown in December and finishing third behind Kauto Star and Denman in the Cheltenham Gold Cup last month.
His rider AP McCoy, the 13-time champion jockey, partnered him in 17 of his 29 races, and said: "That is the saddest thing about horse racing, when things like that happen.
"I had some great days with him - we won a Lexus, a Paddy Power and a Betfair Bowl. He also ran good races in the Gold Cup.
"Horses like him are very hard to replace, both as a racehorse and a character, and someone who will always turn up on the big day for you.
"It is a big blow to his owner, Sir Robert Ogden, and everyone in the stable."
Denman was a short-priced favourite to go one better than when chasing stable-mate Kauto Star in the Gold Cup.
But the Paul Nicholls-trained nine-year-old never looked entirely comfortable, despite making ground to challenge Tom Scudamore and Madison Du Berlais for the lead four fences out.
Denman completely misjudged his jump two fences out, leaving David Pipe's 12-1 shot to pass the post four-and-a-half lengths clear of Exotic Dancer.
Scudamore said: "He's very tough, I was a bit worried when Denman came upsides me - but when I didn't go on, I knew he'd keep on jumping and galloping.
"Denman's a great racehorse and it's a shame to see great champion fall.
"Madison gave me a tremendous thrill. He's been a great flag-bearer for the stable this season.
We haven't had a good season as we would have liked, but days like this make it easier
"We haven't had a good season as we would have liked, but days like this make it easier.
"He's very special to me. He's won a Hennessy [Gold Cup at Newbury] and he's won for me around Aintree. He's been very good to me."
Nicholls said Denman would be put out to grass for the summer and would come back next autumn.
"He is fine apart from a cut to his elbow," said Nicholls. "It was quite a deep cut and he got a good smack on his elbow, but we X-rayed it and it was fine.
"We knew this track wouldn't suit him but he was in the right place at the right time, and would have galloped right to the line."
Thomas added: "He would have won - he just stepped at the fence and I don't know why."
Denman's stable-mate Star De Mohaison's race ended at the first fence as he unshipped Ruby Walsh when getting in too close.
Big Buck's stayed on strongly in the hands of Ruby Walsh to win the John Smith's Liverpool Hurdle.
Sent off the 5-6 favourite, having won the World Hurdle at Cheltenham last month, the Paul Nicholls horse reeled in dual Liverpool Hurdle winner Mighty Man between the final two fences.
After jumping the last the better of the two, Big Buck's surged away to win by three-and-a-quarter lengths.