Tidal Bay got up in the final strides to land what looked an unlikely victory in a thrilling renewal of the Lexus Chase at Leopardstown.
Ruby Walsh got an amazing run out of the Paul Nicholls-trained gelding to pass several rivals on the run-in to give owner Graham Wylie a second Grade One on the card after Back In Focus took the Topaz Chase.
In a bunch finish, Tidal Bay (9-2) snatched the spoils from First Lieutenant, with Flemenstar and Sir Des Champs just behind.
The Neil Mulholland-trained Midnight Chase made the running with Hidden Cyclone and Quito De La Roque on his heels and Tidal Bay held up in the rear.
Hidden Cyclone went on during the final circuit while Flemenstar appeared to be going ominously well as Peter Casey's stable star tried to take his winning sequence to eight, on his first try at three miles. China Rock led two out, but Flemenstar was still going best and landed over the last with the race to win. However, his stamina appeared to give out on the soft ground on the run to the line.
Tidal Bay still had a few lengths to make up but he found what was necessary as Walsh produced him between horses, getting up to score by a head from First Lieutenant with Flemenstar third. Sir Des Champs was just behind but his chances of success were not helped by his jumping.
Nicholls said: "The extra two furlongs at Cheltenham will suit him well. He's in the form of his life for an 11-year-old. Roll on Cheltenham."
Wylie said: "This is up there with Inglis Drever. Back In Focus and now Tidal Bay. Both looked like they were beat over the last and both came with a great run in the end and just nicked it. I thought our fella was cooked four out, but then he started to come again. He's just got guts that horse. Paul has done an amazing job with him and Ruby as well. He gave him a great ride because you have to be patient."
Walsh said: "He jumped the second-last well and I got through the gap going to the last. He was really finishing and I thought I had a chance of getting to them. He was a bit flat-footed at the last and he took time to pick up, but when he did he started to fly and I guess 100 yards down I was thinking I was going to get there.
"Everyone was in the same boat. We all knew Flemenstar's stamina had to be tested and Midnight Chase went a good honest gallop and the tempo was upped all the way. It was a real true-run contest. He's a different horse this year. He won at Wetherby, was second in the Hennessy at Newbury and has come and won today. It's brilliant."
24 April 2014War saunters to easy success
Quevega five-timer still on course
Wylie trio go for Gold
Cyclone blows into Punchestown
Rain set to help Punchestown
Rifles aimed at York
Dante considered for Arod
Carpenter faces stamina question
Tonto strives for Sandown scalp
Telescope sights fixed on Sandown
Prize lined up for Greffulhe raid
Celebration time for super Sire
Taghrooda swerves Sandown heat
Concorde checks in for Punchestown
No Sandown run for Oscar
Un De Sceaux to skip Punchestown
Treve among stellar Ascot entries
Charline still in Guineas mix
Big guns remain in Guineas frame
Prince in Punchestown frame
Sparrow set for Punchestown spin
Balder to take novice test
Connell eager for Tank chase run
23 April 2014Telescope tops Richards runners
No rush for Annie target
Cosgrave appeal set for Monday
Hughes set for Sandown return
France adds flair to Guineas
Mullins drops Vautour Champion hint
Exciting Bunker given Dante date
Culloty keen on Gold run for Heeled
Hannon triple-handed in Guineas
Resurge revived for Epsom return
Sandown option for Battalion
Johnston pair clash in Derby Trial
Reckless Abandon returns to track
22 April 2014Rizeena delights in Guineas workout
Carberry targets swift return
Williamson escapes serious injury
Rizeena thrills Brittain on gallops
Door bags National glory
Twiston-Davies hits four-timer
Joe suffers shock defeat
Scudamore hits century mark
Ivan lands Fairyhouse prize
Thousand shows star quality
Cirrus set for Treve clash
Houblon heads Gold contenders
Guineas still on Berkshire radar
21 April 2014Door bags National glory
Wilson passes away
Ivan lands Fairyhouse prize
Stepper set for trip drop
Richards in Telescope sights
Ladies geared for Summer repeat
Hill out of Irish National
No Dundeel at Royal Ascot
Clowance up for the Cup
Garner hit with lengthy ban
Memories in Final flourish
Fitz powers home at Fairyhouse
Toner hits target for Elliott
Joe ready for Cork outing
Lennon looking to call tune
Ground holds key to Tonto show
Lucky escape for Cook
Mind called up for National service