Defi Du Seuil saw off the veteran Un De Sceaux in a pulsating climax to the Betfair Tingle Creek Chase at Sandown.
Eight runners went to post for the Grade One feature, with the Philip Hobbs-trained Defi Du Seuil the marginal favourite at 2-1, ahead of the five years older Un De Sceaux (3-1) and the grey Politologue - both previous winners of the race.
Ornua took the field along for much of the two-mile contest, before the 11-year-old Un De Sceaux took over racing down the back straight in the hands of Paul Townend.
Barry Geraghty covered the move aboard Defi Du Seuil and the pair rounded the final turn ready to do battle.
Just for a moment it looked like Un De Sceaux had his rival in serious trouble, but Defi Du Seuil managed to get on terms and then looked set to win decisively after touching down in front after the final fence.
However, Un De Sceaux - successful in the 2016 renewal - refused to go down without a fight and came roaring back up the hill, with just a neck splitting the pair at the line.
Only three-quarters of a length away in third was northern raider Waiting Patiently (11-1), who finished to good effect over a trip well short of his best.
Hobbs said: "It was a very long run-in! I thought at the last he would win quite well, but he has run a fantastic race.
"He jumped beautifully and Barry thinks he will have learnt a bit from today - going that pace with Grade One horses.
"Touch wood he is very sound and has a fantastic attitude. I certainly hope so (more progression)."
The Minehead handler was in no rush to commit to future targets, but hinted that plans for Nicky Henderson's dual Queen Mother Champion Chase hero Altior could have an impact.
Henderson has not yet confirmed whether his charge will revert to two miles after suffering his first defeat over jumps at Ascot last month, or step up in distance for the Ladbrokes King George VI Chase at Kempton on St Stephen's Day.
Hobbs added: "I suppose the obvious race is the Clarence House at Ascot, but at this stage we've not thought about it. Today was the main thing then worry about it afterwards.
"Opposition will be important as well, as to what races we might pinpoint. He is very versatile so we could go any trip with him.
"It would have to be considered (if Altior drops in trip). I think we've got lots of options over two miles and further."
Willie Mullins was proud of Un De Sceaux in defeat.
He said: "I'm delighted. I thought he might only be third with about 200 yards to go and then he just seemed to get a new lease of life coming to the winning post.
"If we'd been using the second winning post it might have been the right one for us, but there we are - he's run a cracker.
"He is a remarkable horse. He is an 11-year-old still wearing earplugs, that's how much he wants to get on with his job - he loves it.
"Christmas in Leopardstown might come to soon and I'd say the Dublin Festival (February) would look the one. A lot will depend on what happens to our horses over Christmas."
Esprit Du Large dug deep up the hill to spring a surprise in the Read Road To Cheltenham At racingtv.com Henry VIII Novices' Chase.
Narrowly beaten on his fencing debut at Carlisle in October, the Evan Williams-trained five-year-old went one better at Exeter last month, but faced a big step up in class for this Grade One contest.
Getting weight from his elders, Torpillo was the clear favourite at 13-8, with former Supreme Novices' Hurdle winner Summerville Boy, high-class hurdler Grand Sancy and previously-unbeaten chaser Nube Negra rated his chief threats.
However, Esprit Du Large (14-1) had not read the script, travelling strongly and jumping accurately throughout under Adam Wedge, and he turned for home with only Nube Negra (9-2) to worry about.
Both horses were slick at the final obstacle and with Esprit Du Large refused to bend on the run-in, passing the post a length and three-quarters to the good.
Williams said: "To get runners in these races is very hard. It is great to do it for Mr and Mrs Rucker (owners). I've had a couple of Grade One winners before, but to do it for them means an awful lot.
"I could say lots of things, but they are invaluable and that sums it up. It is emotional. He is a store horse that we bought and he has come through and won a Grade One.
"He is a nice horse. He progressed last time. I just thought looking through them it was worth a crack at it. You roll the dice and sometimes it comes right, but a lot of the time it goes wrong.
"It's my first Grade One in England. I've won one in Wales and Ireland, but never in England.
"Let's see how the form of the race works out. There is one thing for sure, myself and Mr and Mrs Rucker have never been dreamers, and we don't know if this was a good or a bad Grade One yet.
"We will enjoy today and worry about the rest of the season after."
It was a first top-level success for Wedge, who said: "It is what we work for every day - to get a winner like this.
"I've been there (with Williams) since I was a 10lb claimer. It's brilliant."
Dan Skelton was proud of the performance of Nube Negra in defeat.
"His jumping is brilliant and it was a magic run. The ground was a little bit softer than we'd ideally want, but that's no excuse and he's kept on. Credit to the winner, who stayed very well and we couldn't quite get him," said Skelton.
"He'll go to the Kingmaker at Warwick and then Aintree. We'll miss Cheltenham."
Grand Sancy was a long way back in third, with Torpillo fourth.
Summerville Boy made a bad blunder in the back straight and came to grief at the following water jump.