Paul Townend rode Galopin Des Champs to victory to give trainer Willie Mullins his third Gold Cup success in five years.
In an eventful race, Ahoy Senor set the pace until getting too close to the sixth fence from home and crumpling on landing.
Townend bided his time and remained patient, tracking the early pace before getting into contention coming down the hill, tailing Protektorat, Bravemansgame and Hewick, who had been left in front.
He crashed through the third-last, which almost cost him the race, but quickly recovered and by the time American Grand National hero Hewick had come to grief two out, Irish Gold Cup winner Galopin Des Champs had gone upsides Harry Cobden and the Paul Nicholls-trained Bravemansgame.
Both jumped the last on a good stride, but the King George winner could not find the same turn of foot as Townend drew clear.
Galopin Des Champs (7-5 favourite) had seven lengths to spare at the line, with Conflated a further sixth and a half lengths down in third.
After the race, an emotional Paul Townend spoke to Matt Chapman of ITV:
"It wasn't clean that's for sure, everywhere I went I ran into a bit of trouble," said Townend.
"I had full faith in him that he was going to get me out of trouble and he did. Proper, proper horse.
"I was delighted to see them all going at it in front of me. It allowed me to be the last one on the scene.
"This race is just different. It brings winning to a different level"
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