War of Attrition won the Gold Cup in 2006 with rider Conor O'Dwyer
War Of Attrition will bow out of racing after meeting fellow former Cheltenham Gold Cup champion Denman on Wednesday.
The 2006 Gold Cup winner faces the 2008 winner in the Guinness Gold Cup (1730 BST) at the Punchestown Festival.
Twelve horses, including Cooldine and Joncol, have been declared for the highlight of the meeting.
Grand National-winning jockey Tony McCoy retains the ride on Denman after finishing second on the 10-year-old in the 2010 Gold Cup in March.
A high-quality field also includes last year's Punchestown Champion Chase winner Rare Bob and Barber's Shop, who is owned by The Queen.
Irish champion trainer Willie Mullins runs J'y Vole, in addition to stablemate Cooldine, while Philip Hobbs sends Planet of Sound from England.
War of Attrition is a former winner of the Punchestown Gold Cup and another bidding to repeat his triumph at the Kildare meeting is Notre Pere.
"It would be nice if he went out on a good run rather than finishing last," said War of Attrition's trainer Mouse Morris.
"He's been a great servant to the yard - I can only remembering him running one or two bad races in his entire career - and no one can take away his wins in the Cheltenham Gold Cup and the Guinness Gold Cup [also in 2006]."
War of Attrition showed up well in the recent World Hurdle at Cheltenham but faded to finish 12th of 13 finishers.
Owned by Ryanair boss Michael O'Leary, the 11-year-old grey had almost two years out after tendon surgery following his brilliant 2005-06 season.
But he returned to win the Star Chase at Punchestown in October 2008 followed by the Thurles Chase a month later.
Denman has had an in-and-out season. He won under top-weight at Newbury in the Hennessy Gold Cup but subsequently unseated McCoy at the same course before finishing unner-up to Imperial Comander in the Cheltenham Gold Cup.