Sam Waley-Cohen guided Tricky Trickster to victory in the 139th Year Of The National Hunt Chase Challenge Cup, the first race on day two of the Cheltenham Festival.
Nigel Twiston-Davies' 11-1 chance kicked to the front before coming down the hill and was still at the head of affairs turning into the home straight.
He looked a sitting duck when runner-up Drumconvis and Can't Buy Time loomed up before the final fence, but Tricky Trickster found more up the testing incline to score by 10 lengths.
Can't Buy Time, the 4-1 favourite, was held up by JT McNamara at the rear of the four-mile contest.
Although he made stealthy headway from two out, his challenge petered out after the final obstacle.
Another leading contender, Parsons Pistol, made a number of mistakes and was made to pay when coming to grief at the third-last.
Nine De Sivola (16-1) ran an eyecatching race, staying on from out the back to finish third, a further neck in arrears of the winner.
Waley-Cohen said of Tricky Trickster: "He's bit idle, but he's done it really well - unbelievable.
"I kept asking him to pick up and he did every time and that's why he's won it.
"The Irish boys behind me know what they are doing and I thought I might have got there a bit quick, but he stayed on really well."
Twiston-Davies added: "This race has always been the plan.
"Anthony Bromley (bloodstock agent) tells me he's for sale so, please, somebody buy him and send him back to me!
"Because he is a Million In Mind horse he will have to be sold at the end of the season and will go under the hammer at Doncaster in May. But prior to that he may well run in the Scottish National.
"I do hope that whoever buys him might send him back to me."
Trainer Tony Martin said of runner-up Drumconvis: "He made a mistake at the stage of the race when he was just getting into a position, which was a bad time for it to happen.
"It's a hard old race over four miles so I'm not sure he'll be out again (this season), but he should make a lovely staying chaser."