Ruby Walsh conjured a late rally out of Back In Focus to deny Aupcharlie as Willie Mullins claimed a one-two in the Topaz Novice Chase at Leopardstown.
The strong-travelling Aupcharlie was going the better on the run to the final fence but he pecked slightly on landing and could not pull far enough clear of his nearest pursuer.
Walsh kept at the Graham Wylie-owned seven-year-old on the long run-in and the 6-4 favourite battled on bravely to get up close home to score by a head. Texas Jack was third.
Mount Benbulben was pulled up after making a bad mistake as the field went out for the final circuit, while Tony McCoy's partner Jenari fell at the following fence and Lyreen Legend came down three out.
Mullins said: "That's a fantastic win. We didn't think for one minute that Ruby would get back up until he did. He needs every inch of three miles and ground even softer that that. He's a real winter horse.
"As much as I'm delighted I'm sorry for Aupcharlie and Andrew Lynch. It was only his second run over fences and he's run a fantastic race.
"Back In Focus has the RSA written all over him. We'll look for a race over three miles for him.
"With Aupcharlie we could look for the Dr P.J Moriarty. We'll keep them apart. There is no point in them taking each other on again. Aupcharlie could be a horse for the Jewson. The way he jumped he could even come back to the minimum trip. They are two horses to look forward to."
Stan James cut Back In Focus to 12-1 from 16s for the RSA, with Aupcharlie 10-1 from 16-1 for the Jewson Novices' Chase.
Spokesman Joseph Burke said: "Back In Focus proved he's all about stamina after he just got up to prevail by a head on the line from stablemate Aupcharlie, who appeared to just run out of steam. Willie Mullins won the Jewson last season with Sir Des Champs."