Lucayan, trained by Francois Rohaut, came out on top in a desperately tight finish to the Poule d'Essai des Poulains, the French equivalent of the 2000 Guineas.
The much-vaunted Dabirsim did himself no favours by racing keen early on for Christophe Soumillon and suffered serious traffic problems when squeezed just over two furlongs out.
Soumillon gathered his mount to challenge again as his pacemaker Veneto gallantly stuck to his guns in front, but looked to be just running out of petrol as he was again tightened up.
The Aidan O'Brien-trained Furner's Green absolutely flew from the rear, finishing better than anything, but had to settle for third with Veneto second.
There was a sad postscript, however, as Furner's Green had to be put down after breaking a leg passing the winning post, catapulting Joseph O'Brien to the ground.
O'Brien senior said: "Furner's Green broke his off-fore and he had to be put down. Joseph is OK - when a horse goes down at that speed, it could have been much worse."
Rohaut said of the Stephane Pasquier-ridden Lucayan: "I always believed he was capable of winning this.
"He was well-balanced coming into the dip and when I saw how easily he travelled when things quickened in the straight, I thought he would win.
"The others were unlucky on the inside, but that is racing. Two years ago we lost this race, today we won it. He is very good horse and there is still more to come."
The Prix du Jockey Club is not on the winner's agenda, and Rohaut added: "The St James's Palace maybe? No, I think there is the Prix Jean Prat, we'll see."
Christophe Ferland, trainer of Dabirsim, who was sixth, said: "He is unlucky, but he is unlucky at the moment were they quickened and he just doesn't stay.
"He was in a race where there was pace and yes there was a little incident, but if he stayed he would have won.
"He was with the winner when they quickened. Over the mile he just doesn't have the same acceleration he has over seven furlongs.
"We will have to rethink his programme and maybe consider the July Cup."
