Willie Mullins' French recruit made a big impression when winning on his first two Irish starts at Punchestown last season and galloped a couple of rivals into submission when making a winning return at Thurles last month.
With last season's Fred Winter winner Flaxen Flare a significant non-runner, Un De Sceaux was the 1-12 favourite to keep his unbeaten record intact and did so without breaking sweat.
Sent straight to the head of affairs as usual by Ruby Walsh, the six-year-old set a fierce gallop, with Foildubh doing his level best to keep up. However, he was back-pedalling by the time Un De Sceaux rounded the home turn and the odds-on shot negotiated the remaining obstacles to score by 53 lengths with his head in his chest.
Foildubh was so tired that he eventually finished a distant last of three, with Akatara filling the runner-up spot.
Walsh said: "He goes a tremendous gallop. From the last hurdle down the back to the first hurdle in the straight he's maintaining a serious gallop. I couldn't believe when I looked at the back of the third-last how far back Paul (Carberry, on Foildubh) was.
"He wears his heart on his sleeve, he's a very good horse and he's obviously going the right way. If he was to turn up in the Champion Hurdle, I don't think The New One would need a pacemaker!"
Mullins conceded it was likely Un De Sceaux would end up in the Champion Hurdle at Cheltenham in March, but that he has a long way to go to reach the same level as his dual Champion Hurdle hero, Hurricane Fly.
Mullins said: "I'm just looking at where Foildubh finished. He tried to go with him (Un De Sceaux) and a horse rated way below him passed him (Akatara). He just completely choked. Our fellow killed him trying to go the pace.
"He seemed to take the stuffing out of Foildubh and Foildubh is not a bad horse. He beat Rubi Ball last time and he's a decent horse. Our horse was more settled today than I've ever seen him. I don't think he jumped as well as he can, probably because he was going that bit slower."
Asked about future targets, Mullins said: "Ruby just said maybe the Red Mills Hurdle at Gowran - that's an option. I'm going to have a look around and see where I can go. The Red Mills in Gowran time-wise is the right one.
"If he goes to Cheltenham he'll be entered in the Champion Hurdle. I don't see any other race for him there, but he's got to improve a stone to be near Hurricane Fly. I think his French form is on good ground. With his style of running, good ground should be better - it should make it easier for him.
"He's one we're looking forward to all the time."
The New One, who finished runner-up to My Tent or Yours in the Christmas Hurdle, heads the ante-post market for the Champion Hurdle, currently trading at [4.2]. My Tent or Yours, who benefited from his rival's last-flight blunder at Kempton, is the third favourite at [5.7], while dual Champion Hurricane Fly splits the pair trading at [4.5] to retain his title.