Speedy Boarding gave Newmarket trainer James Fanshawe his second victory in three years in the Darley Prix Jean Romanet when bounding home at Deauville.
Successful with Ribbons in 2014, Fanshawe delivered Group One honours again with Speedy Boarding, who was recording her first win at the highest level.
Sayana made the early running until Irish raider Bocca Baciata went on just after halfway.
However, Jessica Harrington's challenger could not keep up the gallop and she weakened in the final quarter-mile.
Speedy Boarding was produced with a well-timed run by Freddie Tylicki and went on to win in good style from Andre Fabre's Ame Bleue with the David Smaga-trained Steip Amach third.
Neither of David Simcock's two runners, Bateel or Carnachy, made the places.
Speedy Boarding took the lucrative prize by a length and three-quarters, and Fanshawe said: "I'm absolutely delighted. She's always been a nice filly.
"Maybe we ran her back a bit quick last time when she disappointed in the Pretty Polly (at the Curragh), but we aimed her at this race and she did it really nicely.
"It's great because it's Freddie's first Group One winner and it's also great for the owners and breeders.
"The ground dried out a bit which probably paid to her strengths."
He added: "She'll be entered in the Prix de l'Opera this week and we have to decide, if the ground is OK, whether we go for that or to Ascot for the fillies' and mares'.
"She's won two Group races in France now."
