The Willie Mullins-trained veteran has won six Grade Ones at or around two miles, including the last three renewals of the Dublin Chase at Leopardstown's Dublin Racing Festival.
But having proved no match for Champion Chase-winning stablemate Energumene at Punchestown in the spring or Blue Lord at Leopardstown last month, connections of Chacun Pour Soi feel the time is right to try something new and he tests the water over two and a half miles in this weekend's Grade Two feature.
Patrick Mullins, assistant to his father, said: "There's been weaker Grade Ones run - it looks a very strong race. Fakir D'Oudairies is obviously one of the top two-and-a-half-mile horses.
"Chacun hasn't always been the strongest of finishers over two miles, but going a half-stride slower will hopefully help him see the trip out.
"He's just getting older now and there's some faster horses in the two-mile division, so we're seeing if we can push him out in trip and we'll see what happens.
"He's been an incredible horse, but time waits for no one, especially in the two-mile division as horses don't get quicker as they get older.
"This will tell us where we're going to go for the rest of the season."
Chacun Pour Soi is set to face five rivals, including two other Closutton inmates in Royal Rendezvous and Haut En Couleurs.
Royal Rendezvous steps back in distance after finishing last of seven over three miles in last month's Savills Chase, while Haut En Couleurs was last seen placing fourth behind another Mullins superstar Galopin Des Champs in the John Durkan at Punchestown.
Mullins added: "Royal Rendezvous was coming off a break in the Savills. He's got a very high mark as he's a Galway Plate winner, I think he'll come forward from that run and I'd imagine he'll probably come forward from this run as well.
"Haut En Couleurs is getting plenty of weight, but on his rating he needs to. We're hoping he'll pick up some prize-money and run well again."
The biggest threat to the Mullins brigade appears to be Joseph O'Brien's Fakir D'Oudairies.
The eight-year-old has won four Grade Ones at the distance, was second in this race last year to the Mullins-trained Allaho and was best of the rest behind Galopin Des Champs last month.
The Mouse Morris-trained French Dynamite and Lifetime Ambition from Jessica Harrington's yard complete the line-up.