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."
25 October 2014Steip shock as Ship sinks
Blaklion sounds War cry
Trophy proves a stroll in Park
Roan reward at last for Wishfull
Muir full of praise for Code
Hawk swoops for Aintree prize
Smaih shines for Hannon
McCoy delighted with World hero
PJA and BHA issue fraud warning
'Enigma' Seanie ready for Knockaire
Prendergast duo set Eyrefield poser
Tac takes aim at Royal-Oak double
Snoano stepping up for Trophy bid
Adelaide rules in Cox Plate
Sir Max clinches Mercury gold
Full marks for Bangor schooling
Milky Way on another planet
O'Brien targets another Trophy
Hurricane in hat for Morgiana
Buick happy as a Star is born
King ace back in the Old routine
McCoy makes Chepstow return
Botti seeking Astrelle celebration
24 October 2014Ballyalton out for the season
Hutchinson sits out weekend action
Balding sweet on Park chance
Walker hoping for Glorious victory
Times out to make Newbury headlines
Cheltenham honour leading figures
Moore keen on Adelaide chance
Stevens back for Breeders'
Johnson Houghton fined
Duke lords it at Carlisle
Southwell first for O'Brien
Fenton fined over steroids
Buywise on the money at Ludlow
Lockinge the big plan for Toormore
Stone ruled out of Old Roan
Wetherby likely for First run
Elm tops Trophy octet
23 October 2014Fenton guilty of drugs possession
Williams hoping for Max power
Harty biding his time with Lane
Clonmel aim for Baily
Jezki possible for Morgiana bow
Harrington expects Naylor to shine
Gosden a Fan of Newmarket scorer
Northern aces face off in Cumbria
Murphy plagued by shoulder injury
Dynaste charts direct Haydock route
O'Brien outlines Breeders' plans
Wetherby-bound Taquin to duck Power
High hopes for Adelaide run
Gilgamboa waits on ground
Dandino misses Cup date
22 October 2014December date for Balding memorial
Deputy outgunned at Fontwell
Whisky chasing Power spoils
Burke maps out Odeliz targets
Present sights set on Power prize
New category for all-weather champs
Moviesta has sales date
National aim for O'Neill star
Cheltenham on Ginge agenda
Lewis eyeing Dubai success
Henderson handed Ascot role
Panther given Breeders' go-ahead
Plain sailing for perfect Storm
Big Easy sets sail for Open fixture
Hall monitored for Giant Bolster
Stomachion in November frame
Hughes revels in 'sweet' success
BHA moves to address small fields
Connell turns to Heskin
Integral to race on next year