Liberty Counsel triumphed in the Irish Grand National at Fairyhouse at odds of 50-1 for trainer Dot Love.
The 10-year-old mare was well beaten at last month's Cheltenham Festival but saw out the three mile and five furlongs well for jockey Ben Dalton.
Away We Go (25-1) was second for trainer Willie Mullins, who saddles the Aintree Grand National favourite On His Own on Saturday.
Home Farm (10-1) came third for Arthur Moore with Sweeney Tunes (12-1) fourth.
Romanesco, who was third when Liberty Counsel finished 13th at Cheltenham, looked set to challenge for a place but fell at the last.
Dalton, riding in the race for only the second time, was hard at work turning for home and his mount appeared at the mercy of Away We Go, with Paul Townend looking for dangers after jumping the second-last fence.
There was little to choose between the pair jumping the final obstacle, but Liberty Counsel dug deep to take the prize by half a length.
The surprise result means Mullins, who won the national at Aintree with Hedgehunter in 2005, is still searching for a first victory in the Irish version.