Allaho won a record eighth John Durkan Memorial Chase for Willie Mullins at Punchestown with the trainer's son Patrick the triumphant jockey.
This year's Ryanair Chase winner at Cheltenham almost fell at the second last, but regrouped to hold off another Mullins horse, 20-1 shot Janidil.
Melon, priced at 50-1, sealed a Mullins one-two-three in the Grade One race.
Henry De Bromhead's 7-4 favourite Envoi Allen, with Rachael Blackmore on board, finished a disappointing sixth.
Mullins' Asterion Forlonge also looked to be travelling well approaching the third last, only to unseat Bryan Cooper.
A brilliant winner at last season's Cheltenham Festival, Allaho was a 7-2 shot to make a successful reappearance in a race in which champion trainer Mullins saddled seven of the 10 runners.
Sent straight to the lead, the Cheveley Park Stud-owned seven-year-old jumped well in the main - apart from almost coming to grief at the second last - as he bravely stayed to clinch a two-length victory.
Willie Mullins' fourth successive win in the chase makes him the most successful trainer in the history of the race. He was previously tied on seven victories with Jim Dreaper.
Bryony Frost was unable to repeat her big Irish Grade One success on Frodon at Down Royal in late October as she finished seventh on another of Mullins' contenders Franco De Port. This year's Grand National winner Minella Times fell at the third last to complete a disappointing race for De Bromhead.