Ed Walker's Dreamloper was a convincing winner of a dramatic renewal of the Prix du Moulin at ParisLongchamp.
The mare was partnered by Kieran Shoemark for the one-mile contest and faced a field of nine rivals, which included 2000 Guineas winner Coroebus.
But as Charlie Appleby's Coroebus was making his challenge around a furlong and a half out he crashed to the ground under William Buick.
Shoemark was clear of the field and of any danger at that stage and cruised to a comfortable five-and-a-half-length victory at 17-2.
But while Buick was able to get to his feet, it was subsequently confirmed Coroebus - who also won the St James's Palace Stakes - had suffered fatal injuries.