Paul Cole's Mr Dinos, just fifth in the St. Leger, was the star of the show in the French equivalent, the 1 7/8-mile Prix Royal-Oak, at Longchamp on Sunday.
The 3-year-old led a one-two British effort with John Gosden's Sulk, finishing in second, beaten 2 1/2 lengths.
Morozov provided the best finish of the French in third, but was demoted to sixth after a stewards' inquiry found Andre Fabre's runner guilty of hampering fifth-place Terrazzo.
Clety, ridden by Breeders' Cup Mile winner Thierry Thulliez, was placed third.
Mr Dinos won for the second time in France. He captured a Group III at Vichy in July.
He led from the start under Dominique Boeuf. The heavy sod was ideal for Mr Dinos, who reserved his early speed for a strong finish.
Richard Gibson's Cut Quartz, third in the Prix Cadran on Arc weekend, was last of the seven runners this time.
Mr Dinos was the first English Royal-Oak win since the 1994 victory of Barry Hills' Moonax.