The Rebecca Curtis-trained O'Faolains Boy (12/1) just about got the better of Smad Place after a prolonged battle to win the RSA Chase at Cheltenham under Barry Geraghty.
The front two finished well clear of Irish hopeful Morning Assembly, with Ballycasey (13/2jf) fourth after weakening in the straight.
Corrin Wood set the pace in the extended-3m event for novices with Annacotty and Ballycasey in close attendance.
The young chasers jumped well early on but blunders began to creep in on the second circuit and the number of contenders had thinned considerably by the top of the hill.
Ballycasey was bidding to give the Willie Mullins-Ruby Walsh team their fourth winner of the week and swept into the lead on the run to the third from home but he was joined at the head of affairs by Smad Place (13/2jf).
And it was Smad Place who edged ahead as they turned for home but, while Ballycasey fell away, O'Faolains Boy loomed up approaching the last.
The duo jumped that one together and then became embroiled in a thrilling battle up the run-in, with the winner eventually prevailing by a neck after producing a late surge.
Morning Assembly (9/1) stayed on to finish six lengths back in third but the well-fancied Carlingford Lough could never quite get into the race under Tony McCoy.
The winner was following up his victory in the Reynoldstown Chase at Ascot and Geraghty said: "He just ran in snatches a little bit. He didn't jump as well as he did in Ascot.
"I was never happy and never thought I'd win but, in the last mile, he started to come alive a little bit. He got there, slightly under sufferance
"There's improvement in him. He didn't feel as good today as he did at Ascot for some reason and he didn't sparkle, but he's still won."
Winning trainer Curtis added: "Before Christmas our horses weren't running great but they are now and we knew he was very well coming here.
"He twisted his shoe quite badly but it didn't stop him in the end. He's a funny horse, he finds a wind then goes again.
"It's not a massive surprise as he proved at Ascot he was decent but you never expect to win here."
Smad Place's trainer Alan King was magnanimous in defeat and said: "We've got beat by a better horse, but I'm thrilled with him.
"We always hoped he would be as good a chaser as he was a hurdler and he's going that way. The ground drying out was not a problem for him. I'd have loved to have won, but he did great."
Pat Fahy, trainer of third-placed Morning Assembly, said: "It was a rough enough race and he got into a bit of bother, but I'm delighted with the run in the circumstances.
"It was only his fourth run over fences and it was very quick ground but he stayed very well and his heart got him to finish where he did.
"Davy (Russell) said he'd never ridden in an RSA when they'd gone so quick. The horse will definitely go to Punchestown."
Sky Bet quote both the winner and runner-up at 20/1 for next year's Gold Cup and Rebecca Curtis said of O'Faolain's Boy: "Everyone wants a Gold Cup horse, and you never know, if he keeps progressing he might be one day. The Gold Cup next year would be the dream."
Sky Bet spokesman Michael Shinners said: "Until we see how Bobs Worth and Silviniaco Conti get on on Friday, it's hard to price the race up more fully, but O'Faolain's Boy certainly looks a contender already and the runner-up has plenty of Festival form!"