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.'
Asked about Barzalona, Fabre said: 'He is a home-bred jockey and I had total confidence in him. He is only 19.'
Barzalona said: 'I always felt confident during the race, and even though I was at the back the other good horses were just in front of me. For a while I thought I would be fourth or fifth, but he just accelerated.
'It is fantastic and I don't realise yet what has happened.'
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.'
Connections of Carlton House felt the colt did not get the run of the race.
John Warren, the Queen's racing and bloodstock advisor, said: 'Ryan (Moore) is disappointed, but said it was a messy race and the horse marginally missed the kick.
He said a few horses, the long outsiders, came back on him and that didn't help him get into that smooth rhythm he wanted. As a consequence he had to make his run from further back than he wanted.
'He felt if the circumstances had been different so would the result. I would say it was just the run of the race that did us no favours. If he takes on the same horses again who knows the result might be different.'
Carlton House was only declared fit to run on Friday after overcoming an injury scare. His trainer Michael Stoute said: 'He's run very well, but things just haven't gone right.
He had a hold-up close to the race and during it he got too far back and then had to run wide into the straight. He's still a high-class colt and he will have a big day.'