Long Dog led from start to finish to claim the Paddy Power Future Champions Novice Hurdle at Leopardstown.
The Willie Mullins-trained four-year-old was bidding for his sixth straight victory and his second at Grade One level, having seen off stablemate Bachasson in the Royal Bond at Fairyhouse last month.
The two stablemates locked horns once more, with Long Dog narrowly leading Bachasson for much of the two-mile journey, before the latter began to falter from the home turn.
Gordon Elliott's Tombstone and another Mullins inmate in Petit Mouchoir emerged as the biggest threats on the run to the final flight, but 9-4 favourite Long Dog dug deep to prevail by three-quarters of a length.
Tombstone was the same distance in front of Petit Mouchoir at the line.
Winning owner Rich Ricci said: "He's very brave and he clearly wants further - Ruby (Walsh) said he was flat out the whole way.
"The ground was a bit too heavy for him, but he won that very well.
"He'll definitely go up in trip, but I'm not sure whether he'll run between now and Cheltenham - he seems to take his races very well.
"I'd be happy to go straight to Cheltenham, but it's Willie's call.
"He's a grinder."