Florida Pearl reversed last year's placings with Native Upmanship in the featured John Durkan Memorial Chase when he held on by the minimum margin in a thrilling finish under Paul Carberry.
Sackville, winner of the Charlie Hall Chase at Wetherby last month, was sent off the easy-to-back 6/4 f (from 1/1) and rider David Casey wasted no time in seizing the initiative after flagfall.
Closely tracked by Rince Ri, whose jumping let him down on more than one occasion, the contest began to unfold after the 3rd last with Sackville still holding the call.
Florida Pearl swept past the tiring favourite after the second last fence but then needed all of Paul Carberry's urgings on the run-in to hold the late rally of Native Upmanship by a rapidly diminishing short head.
Winning trainer Willie Mullins still has the Gold Cup at Cheltenham next March as the long term target, 'The Gold Cup is still on and his other target next year is the Hennessy Gold Cup at Leopardstown.'
On more immediate plans, Mullins, who landed the opener with One Night Out (Ruby Walsh) added, 'Before that I'm keen to have another crack at the King George at Kempton over Christmas.'
Joe Crowley whose daughter Frances trains Sackville was not too downbeat with Sackville ' That's the third time he has got beaten here and it's never easy having to make the running. It just wasn't his day.'
Cashmans reacted by cutting Florida Pearl to 20/1 (from 33/1) for the Gold Cup while Sackville was eased to 10/1 (from 7/1) and Rince Ri 33/1 (from 20/1) for the Festival highlight.
Risk Of Thunder's recent domination over the banks at Punchestown came to an end when Ken Whelan's mount over jumped the 18th , a drop fence with a hedge, and suffered a crashing fall.
His exit left market rival Linden's Lotto in front and, under a confident Paul Carberry, the Tony Martin-trained 12yo came home twelve lengths clear of Bangabunny.
Risk Of Thunder, who notched up his 6th successive victory in the La Touche Cup at the 2000 NH Festival, was quickly remounted and to his credit safely negotiated the remaining 5 fences to fill 3rd spot, 20L adrift of the 5/2 winner.
Paul Carberry completed a wonderful afternoon when he completed a treble aboard Falcon Du Coteau (4/1-11/4f), also trained by Tony Martin.
Barry Geraghty was another pilot in form, initiating a brace on the very promising Ballyhamshire Boy for Sean Aherne in the 2m novice hurdle before teaming up with Tom Taaffe's Be My Case in the Toe Exacta Handicap Hurdle.
John Hassett, who saddled 16/1 shot Future Strike to finish 9th behind Ballyhampshire Boy, was in trouble with the stewards afterwards.
Hassett was fined #500, the horse banned for 42 days and rider Philip Carberry suspended for 12 days for insufficient effort.
On a day when favourite backers enjoyed a profitable session Pre Ordained (5/1-7/2f) and Davy Russell landed the finale.
