Halcon Genelardais defied 11st 3lb to run out a gutsy winner of the Coral Welsh National for Alan King and Wayne Hutchinson.
The 7-1 chance was always travelling well in the Chepstow marathon and took up the running approaching the third-last fence.
Having touched down with a couple of lengths in hand of his pursuers, King’s charge then dug deep and fought on bravely to repel 14-1 chance Mon Mome by four lengths.
Juveigneur stuck on well to claim third, while Lordofourown finished fourth.
Hutchinson had settled the six-year-old in mid-division for much of the contest as Naunton Brook and One Knight set a strong gallop.
Many had cried enough by the time the field swung for home for the final time, but the well-supported Lou Du Moulin Mas was travelling menacingly well along with Mon Mome, who had gradually crept into a challenging position.
Halcon Genelardais was also still moving strongly, however, and he put his seal on the valuable contest with a flying leap three-out.
Mon Mome and Juveigneur refused to give in and kept chasing King’s charge but never looked like overhauling him.
The former had to settle for second spot while the latter, an 11-1 chance, hung on grimly for third, six lengths behind the runner-up.
Irish raider Lordofourown, also sent off at 11-1, came from the clouds to fill fourth spot and reward each-way punters.
Noel Williams, assistant trainer to King, told BBC Sport: “He’s got great character and he’s a thorough stayer. He has a big future as he’s only six.
“It (this race) had been in the pipeline for a long time and Alan thought he was ideal for the race. He doesn’t get it wrong often.
“It was fantastic and it was a bit of a boost beforehand as Wayne rode a winner earlier. He’s going from strength to strength and he’s a great jockey.”
Hutchinson added: “He’s a pleasure to ride, but for the first mile I was a bit worried – he curled up into the first fence and he wasn’t enjoying it.
“But he turned into the straight and picked up the bridle for the first time and from then on he travelled like a winner the whole way. He galloped all the way to the line.
“It’s fantastic – the kind of thing you dream about. Hopefully it’s the first of many more.”
Venetia Williams said of the runner-up: “We are absolutely delighted with that. Coming from the fourth-last to third-last I thought we might win but we are very happy and that was always his plan.”
Nicky Henderson said of the third: “It was a super run. He was going so well but we know now he doesn’t stay real distances.
“He is not a slogger and I’d have thought something like the Betfred Gold Cup might be for him again.”