A field of 10 runners went to post for the Group One contest including a trio of British challengers in Harry Dunlop's Robin Of Navan, the Clive Cox-trained My Dream Boat and Charlie Appleby's Godolphin runner Hawkbill.
Hawkbill hit the front early in the home straight, but his effort petered out, while Robin Of Navan weakened very quickly and was virtually pulled up.
My Dream Boat was in there pitching in the final furlong, but try as he might, he could not get by last year's winner Silverwave, and Alain de Royer-Dupre's Zarak swooped late under Christophe Soumillon to beat them both.
It was a first win at the highest level for Zarak, who is a son of Dubawi out of the great racemare Zarkava.
Royer-Dupre told Equidia: "I'm relieved, it's good to see the real Zarak, he needs a bit of time to get on his feet."
Soumillon said: "I had so many disappointments with him, he's a horse with problems.
"Alain told me he had him like never before."
My Dream Boat was narrowly beaten to third place by Armande.
Doha Dream was being produced with what looked a threatening run on the rail two furlongs from home when he became short of room and unseated jockey Gregory Benoist.
Elas Ruby fared best of the British raiders in the Prix de Malleret later on the card, finishing third for John Gosden.
The Group Two heat produced a thrilling finish, with Andre Fabre's Strathspey just pipping the Freddy Head-trained Listen In in a photo.