Chicago Grey boosted his claims for the John Smith's Grand National when springing a 25-1 surprise in the Red Mills Chase at Navan.
The Gordon Elliott-trained outsider of four led between the last two fences before going on to defeat Foildubh cosily in this two-and-a-half-mile heat.
Rubi Light set out to make all the running in his bid to lift this Grade Two prize for the third successive year, but he never looked like winning after being headed before the third-last.
Hidden Cyclone also disappointed and he too was well-beaten when he fell at the final fence.
Meanwhile, Chicago Grey travelled kindly for Davy Condon and was too strong for Foildubh in the closing stages, although the pair were separated by the width of the track.
Elliott said of his two-and-a-half-length winner: "I thought he'd run well. He's had a wind-op and obviously the Grand National is the plan now.
"The ground was soft and it played into his hands. He'll go straight for the National now and I'd say the wind-op made a big difference to him."
On His Own (10-1), trained by Willie Mullins, also enhanced his Grand National prospects when making a winning return in the Ladbrokes Boyne Hurdle.
While his odds-on stablemate Thousand Stars trailed home last of the six runners, the Graham Wylie-owned nine-year-old could not have done any more on his first race since last April's Aintree showpiece.
Si C'Etait Vrai made a bold attempt to make all, but he could not match On His Own's challenge under Paul Townend from the last two flights.
However, the Gigginstown House Stud-owned chaser plugged on gamely to hold Un Beau Matin, in the same colours, for second place.
Mullins said of his two-and-a-quarter-length winner: "I've been trying to find a suitable hurdle race for him. He was a novice (over hurdles) before today but he's won a nice prize over hurdles now.
"Coming here today, the plan was to give him another run over fences before the National but after winning today, we might review that and he could have another run over hurdles."
Mullins blamed the ground for the poor showing from Thousand Stars.
"Ruby (Walsh) said he just couldn't handle the ground. He came back in with muck halfway up his knees and just seemed to sink into it," he said.
"He's unlikely to run at Cheltenham as the Aintree Hurdle is the one race we really have in mind for him."
Buckers Bridge (7-2) edged out Twinlight in a thrilling finish to the Flyingbolt Novice Chase.
Twinlight looked like striking for Mullins and Ruby Walsh when holding a narrow lead after jumping the last.
However, Buckers Bridge rallied under a hard drive from Andrew Lynch to get up in the final strides for trainer Henry de Bromhead.
De Bromhead said: "He just wasn't right at Fairyhouse (fifth in the Drinmore Chase) the last day so we backed off him and gave him a bit of a break. He seems to be back as good as ever.
"He jumped super and battled well. I hope that trip was a bit sharp for him and we'll step him up a bit in distance.
"He's entered in the Jewson at Cheltenham. I also put him in the novice handicap chase but he probably won't be qualified for that now."
There was another victory for the Mullins yard when Terminal took the Irish Form Book Ten Up Novice Chase in the hands of Ruby Walsh after a duel with the odds-on Tofino Bay.
The winning six-year-old (15-8) tracked He's A Delight for much of the way as the jockeys looked for the best ground, and challenged two out before being driven clear to win by five and a half lengths.
There was an upset in the two-mile maiden hurdle when Harry Rogers' Irish Thistle (9-2) dismissed the odds-on City Slicker, while the two-and-a-half-mile maiden hurdle was won cosily by Noel Meade's 7-4 favourite Mullaghanoe River, completing a Condon double.
Mullins made it a treble when his son Patrick drove up Made In Germany (9-10 favourite) to snatch the Dunsany INH Flat Race close home.