Ioritz Mendizabal brought the Jean-Claude Rouget-trained filly with a telling run on the outside to lead in the dying strides of the 10-furlong contest.
The hot favourite got the better of the Aga Khan’s Sanaya by half-a-length with Alix Road a neck behind in third.
“I knew she was going to win 200m out. She’s very good, and that race will have taught her a lot,” said Rouget.
“She’ll be one of the favourites now for the Diane, we’ll see what happens in three weeks.”
Laverock, disqualified from third place in last year’s French Derby, resisted the late flourish of Manduro to grab Group One glory in the Prix d’Ispahan.
The four-year-old, owned by the Gainsborough Stud and trained by Carlos Laffon-Parias, took the lead from his stablemate Krataois inside the final half-furlong.
But he had to be ridden out all the way to the line by David Bonilla to hold the fast-finishing Manduro by a neck.
Laffon-Parias said: “He’s a hard horse to get ready as he does nothing in the mornings. He was logically disqualified in the Jockey-Club.”
Bonilla added: “Once he got relaxed he accelerated well. I said the first time I rode him he was Group standard, and he’s proved it here.”
Hughie Morrison’s 11-year-old Alcazar put up a bold bid in the Group Two Prix Vicomtesse Vigier before fading into sixth behind Shamdala.
The veteran tried to make all the running but he dropped out of it in the straight and finished last of the six-runner field, although he was only beaten four lengths.
Shamdala just held Montare by a nose to give the Aga Khan handsome compensation for the defeat of Sanaya.