Hot favourite Battaash proved a bitter disappointment as Kevin Ryan's filly Glass Slippers ran out a dominant winner of the Prix de l'Abbaye at ParisLongchamp.
So impressive when landing this race two years ago, the Charlie Hills-trained Battaash was the odds-on market leader to regain his crown off the back of what was arguably a career-best performance in the Nunthorpe at York in August.
But his trademark lightning speed was missing from an early stage as he floundered in the testing conditions - and he dropped back quickly through the field late on.
Glass Slippers was stepping up to Group One level for the first time after landing a Listed prize at Deauville and a Group Three over this course and distance on her last two starts.
The 20-1 shot was smartly away in the hands of Tom Eaves and never looked back after taking over the lead from fellow Yorkshire raider El Astronaute - bounding clear to claim an emphatic victory.
Aidan O'Brien's So Perfect was second, with El Astronaute third, James Tate's Invincible Army fourth and last year's winner Mabs Cross fifth for Michael Dods.
Eaves said: "We came here with a question mark over the ground, but we know she likes her travelling and she gave me a great feel all through the race."
Shropshire-based owner Terry Holdcroft said: "She's been here (France) four times and she's won three out of three as on the other occasion she had gravel in her foot and couldn't run. I came here happy to be placed and to be honest, we didn't think we'd win. We will keep her in training next year."
Charlie Hills could offer no excuse for the listless performance of Battaash.
"I'm really scratching my head as two (furlongs) out he was the first one beaten and he really never raised a gallop," said the trainer. He's not blowing inordinately hard, but it was certainly not him by any stretch of the imagination. We will have to take him home and see if anything shows itself."
Jockey Jim Crowley added: "I was the first beat. He felt very flat - not like Battaash at all - and there's no explanation."