British raider Custom Cut dominated from the front in the Ard Glen Construction Amethyst Stakes at Leopardstown.
David O'Meara's charge brought strong course form to the Foxrock circuit, having twice won at the track, and was a 9-2 shot under Daniel Tudhope.
The eight-year-old was soon bowling along at the head of affairs and while the Dermot Weld-trained Raymonda was produced with what looked a timely challenge by Pat Smullen, Custom Cut stuck to his guns admirably to seal a half-length success.
Cougar Mountain finished strongly to take third place, another nose in arrears.
Tudhope said: "He obviously likes it here. I wanted to make it a good test of stamina as he's a tough horse to pass.
"To come back here and win a Group Three, he's still got it."
O'Meara said: "He likes it around here. He won the Boomerang a couple of years ago and was second in it last year.
"Ideally, he wants a little more juice in the ground but he's an older horse and he's very sound.
"I thought it was a brilliant ride by Danny. He made it a good test, and I thought the horse did very well.
"I'm not really sure where he will go next. We are a little bit different with him this year as he normally wins a Group race at the back-end of the season and then carries a penalty all year which made the early season options a bit hard.
"This year he has a bit more scope to pick and choose his races.
"We'll give him a couple of weeks and he'll be out again. He'll go for another Group Three or go back up to a Group Two.
"He'll more than likely come back here on Irish Champions Weekend for the Boomerang and also later in the year the Joel at Newmarket.
"They are the two races that he likes."