Neptune Collonges, an 8-1 shot ridden by Ruby Walsh and trained by Paul Nicholls, won the Grade One Guinness Gold Cup at Punchestown on Wednesday.
The three-mile chase was worth 150,000 euros to the winning stable.
Kingscliff (16-1), who led for the early part of the race, came home in second with In Compliance, the 6-4 favourite, running in third.
Racing Demon was fourth but the 2004 winner Beef or Salmon and Cloudy Bays trailed in at the back of the field.
The winning margin for Neptune Collonges was three and a half lengths.
It was the third career win, from three runners, at Punchestown for Nicholls.
He said the winner, rated a general 20-1 chance for the 2008 Cheltenham Gold Cup, would only run in that race if the ground conditions were soft.
"Today was his Gold Cup," he said of the six-year-old.
The champion English trainer indicated Neptune Collonges might be a Grand National contender at some stage, although probably not next season.