Sizing Granite turned what looked a competitive Guinness Handicap Chase into a procession in the hands of Robbie Power at Punchestown.
The nine-year-old won a Grade One novice chase at Aintree for Henry de Bromhead two years ago, but has been largely disappointing since.
He joined Colin Tizzard prior to the start of the season and after having a spin over hurdles at Taunton last month, he was a 14-1 shot on his return to fences.
Sizing Granite jumped and travelled powerfully and came home comfortably clear of stablemate Viconte Du Noyer.
Power was completing a double on the day for his retaining owners Ann and Alan Potts after winning the Punchestown Gold Cup on Sizing John.
The jockey said: "I rode this horse over hurdles at Taunton. He finished fifth and thought he should go to the sales.
"Colin told me I should ride him. He said he was in great form and was working the best he'd seen.
"Colin is a genius and this has been unbelievable."