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 the two-and-a-half-mile heat run in testing conditions.
Chicago Grey travelled kindly for Davy Condon at the rear of the field all the way and was too strong for Foildubh in the closing stages, although the pair were separated by the width of the track.
Rubi Light set out to make all the running in his bid to lift the 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.
Elliott said of his two-and-a-half-length winner : "I thought he'd run well. He's had a wind op and 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."
Boylesports cut Chicago Grey to 25-1 from 33-1 for Aintree and Ladbrokes go 20s.