Snow Fairy gained a dazzling success over Nathaniel in the Red Mills Irish Champion Stakes at Leopardstown.
Ed Dunlop's globe-trotting mare settled nicely for Frankie Dettori and always looked to have Nathaniel covered as he was driven to overhaul pacemaker Daddy Long Legs rounding the bend.
Nathaniel (13-8 favourite) was in front and kicked on entering the straight, but Snow Fairy (15-8) quickened smoothly to take closer order and was always on top as the line approached.
St Nicholas Abbey ran a gallant race as he tried to close in third.
Dettori, who had made the dash to the Dublin track in a helicopter from Haydock with Nathaniel's jockey William Buick, was deputising on Snow Fairy for the injured Ryan Moore.
He had also ridden Snow Fairy 12 months ago when Dunlop's star found only So You Think too good.
The Italian's delight was clear as he performed his famous flying dismount, much to the delight of the crowds surrounding the winner's enclosure.
Snow Fairy had only recently returned from a serious leg injury when winning the Prix Jean Romanet at Deauville, and was taking her Group One haul to a magnificent seven.
Dettori, winning his fifth Irish Champion, said: "Usually I don't notice these things, but I could hear the crowd really get behind her and the roar when she crossed the line"
He added: "The crowd at Leopardstown are fantastic. I've had some great days here.
"It's all about the filly, she's so popular. Everyone was delighted to see her win like that in a fighting finish. She got a tremendous cheer.
"She's a popular as Kauto Star over jumps and for racing we need superstars like that. She's small but she comes with a big punch!
"All the credit goes to Ed and the team for bringing her back after her serious injury, this race has been won by some great champions and she is one of them.
"It has been an honour to be on her again. Ryan said be patient and she'll quicken when you ask her. Ryan has been a gentleman, a great help."