Pour Moi snatched victory in the shadow of the post to land the Investec Derby at Epsom from Treasure Beach and the Queen's Carlton House.
Mickael Barzalona, 19, gave the Andre Fabre-trained colt an ultra-confident ride and dramatically celebrated before the line as he got up to win the premier Classic at his first attempt.
Pour Moi (4-1) pipped Treasure Beach (25-1) by a head with Carlton House, the 5-2 favourite, three-quarters of a length away third.
Joseph O'Brien, also making his Derby debut, set the pace on Memphis Tennessee, trained by his father Aidan.
He held a six-length lead with big outsider Marhaba Malyoon as they made the descent to Tattenham Corner, where Ryan Moore was pushed wide on Carlton House.
Treasure Beach, another O'Brien runner, hit the front with Carlton House trying to make his bid and Native Khan and Recital not far behind.
But Pour Moi came from even further back to launch his bid and grab the spoils, giving the Coolmore triumvirate of John Magnier, Derrick Smith and Michael Tabor the first and second.
Fabre said: "He is such a good horse. He accelerated twice, once to catch up and then again.
"It is such a pleasure to win this race with my young jockey in front of a big crowd. I couldn't be more happy."
Tabor said: "It was sensational. He was at the back of the field, but we always knew he had to ridden that way. It was a tall order to do it like that, but we knew he was very good and it's not a surprise.
"I could always see him winning from what Andre had told us about the horse.
"We wanted to win, obviously, it goes without saying - but one thing is for sure and that is if we hadn't we wanted the Queen's horse to win."
Smith had Treasure Beach running in his colours and said: "You don't ask Andre (to run), he tells you. I was cheering Treasure Beach without seeing where Pour Moi was coming from."
Coolmore supremo Magnier said: "I wish that someone else owned the third horse, but that's racing.
"Andre was confident all the way for the last few weeks. He said how he was going to be ridden and said he had more speed than (Arc winner) Peintre Celebre. He was confident."