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 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, with Ruth Jefferson's stable star bouncing right back to his best to offer plenty of hope for the rest of the campaign.
Sky Bet cut the winner to 4/1 from 5/1 for the Betway Queen Mother Champion Chase. Spokesman Michael Shinners said: "Defi Du Seuil showed his class and won what was a tremendous race. Options are very much open for connections but the Queen Mother could well be the long term target and he's clearly a major player."
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 Boxing 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."
Only three-quarters of a length away in third was Waiting Patiently, with Ruth Jefferson's stable star bouncing right back to his best to offer plenty of hope for the rest of the campaign.
Jefferson said: "At the moment gutted is overtaking thrilled! Brian (Hughes) said he got a bit wound up by the false start. I don't think he got outpaced, I just think he got a bit surprised coming back to two miles
"He travelled well and jumped well and has stayed on like an express train. I don't know what we do know as there aren't many two-and-a-half-mile races about, that is the problem."