Editeur Du Gite and Edwardstone served up a thriller in the Albert Bartlett Clarence House Chase at Cheltenham with Niall Houlihan on the former getting the better of a photo finish.
Gary Moore's 14/1 shot set the pace out in front in the rearranged Grade One contest, with Amarillo Sky joining him in the early exchanges.
Champion Chase star Energumene, who was beaten in an epic race by Shishkin last year at Ascot, stalked the pace under Paul Townend and delivered his challenge before the last.
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Tom Cannon on Edwardstone, the 2022 Arkle and Tingle Creek winner, came from the rear and was the widest of the three at the last, picking up and heading the eventual winner in the final furlong.
Energumene's chances of victory were burst with a last flight error, staying on for a distant third in the end.
Meanwhile up ahead, Houlihan and Editeur Du Gite rallied on the run-in to get back past Edwardstone and claim a famous victory for the Moore team.
Sky Bet reacted by easing Energumene to 6/4 from 4/6 for the Champion Chase in March, while Edwardstone shortened to 7/4 (from 9/4) and Editeur Du Gite was cut to 9/2 (from 16s).
Josh Moore, representing his father Gary at Cheltenham, said: "The good thing is Edwardstone came to him and looked like he was going to go on and win the race, but he has fought back at the end.
"I was a little surprised to see that, in the sense that when he was a novice he used to be a weak finisher at the end of his races and he is actually finishing his races much better as he's got older.
"Perhaps he has got better stamina now. It could be a maturity thing."
He went on: "There are three in the Champion Chase now. He definitely has the right to be in it. Not so long ago we thought we would go for the Game Spirit and then wait for the Celebration at Sandown and miss Cheltenham because the others would be targeting it.
"All being well, he will come back for the Champion now, I should think."
Comfort Zone & Scriptwriter battle it out in Triumph Trial
Comfort Zone further highlighted Ireland's dominance in the juvenile hurdle division when landing a telling blow in the JCB Triumph Trial Juvenile Hurdle.
Joseph O'Brien's youngster made a successful raid to British shores when taking the Finale Juvenile Hurdle over Christmas and added a second successive Grade Two prize when downing Milton Harris' Scriptwriter - who headed into the Cheltenham feature as one of the home team's best Triumph Hurdle hopes.
Scriptwriter looked to be travelling beautifully as Paddy Brennan charted a typically wide course round Prestbury Park, but the 2/1 favourite Comfort Zone was smuggled into contention by Jonjo O'Neill Jr and having jumped the last level pulled out more on the run to the line to prevail by half a length.
The winner was cut to 10/1 from 14/1 by Betfair for the Triumph Hurdle at the Festival, while he is 7/1 from 8s for the Boodles Fred Winter.
Syd Hosie's Rock My Way also stated his claims for the Festival when a taking winner of the Ballymore Novices' Hurdle.
Second to Nigel Twiston-Davies' Weveallbeencaught on his rules debut over the track and trip on New Year's Day, he built on that performance to record a length and a half success in the hands of Tom Scudamore.
The 13/2 winner was shortened to 16/1 from 50/1 for both the Ballymore Novices' Hurdle and the Albert Bartlett.
Back On The Lash scores for Harry Redknapp
Back On The Lash, owned by Harry Redknapp, defended his Glenfarclas Cross Country Handicap Chase as Festival hero Delta Work had to settle for third at Cheltenham.
Delta Work was the villain of the piece at Prestbury Park in March when defeating Tiger Roll in the dual Grand National winner's final outing, and Gordon Elliott's veteran was sent off the 5/2 favourite for handicap action on this occasion.
However, the task of conceding weight to all but one of his 15 rivals took its toll and allowed Martin Keighley's charge to taste success over the cross-country circuit for a second time.
Sean Bowen expertly navigated the unique course in the centre of the track to bring the 6/1 shot home three-quarters of a length in front of Deise Aba.
Coral went 16/1 for the nine-year-old to thrive again at the Festival in March, with Betfair 20/1.
Stage Star jumps into Festival contention
Stage Star put himself in the Cheltenham Festival picture with a fine display of jumping.
A Grade One winner over hurdles, Paul Nicholls' seven-year-old was making just his fourth start over fences having got his chasing career back on track at Plumpton earlier this month.
Sent off the 11/4 favourite for the Timeform Novices' Handicap Chase and carrying top-weight of 12st, the son of Fame And Glory produced an exhibition round from the front end to coast home the best part of four-lengths clear of runner-up Datsalrightgino in the hands of Harry Cobden.
In the aftermath, Coral went 10/1 from 25s for the Grade One Turners Novices' Chase at the Festival.