Racing: Aidan and Joseph O'Brien failed in their bid to complete a Derby double as Imperial Monarch finished a luckless eighth behind shock Prix du Jockey Club winner Saonois.
The father-son combination headed to France following a fantastic day at Epsom, with 2000 Guineas hero Camelot completing a Classic double in the Investec Derby, sparking dreams of the Triple Crown.
The unbeaten Imperial Monarch appeared a leading candidate for the French equivalent following his victory in the Sandown Classic Trial last month, but found himself last turning for home after being shuffled back in a rough race.
Switched wide to challenge in the straight by O'Brien junior, the three-year-old found top gear and was flying at the finish, but was unable to reel in the leading group.
The jockey said: "It was a very rough race."
The honours went to Saonois, trained by J-P Gauvin and ridden by Antoine Hamelin, who only lost his claim this year and is apprenticed to Alain de Royer-Dupre.
"There was no real pressure as we didn't have a great draw and my trainer just said I should ride him the best I could," he said. "I have never ridden in a Group One race before and winning the Prix du Jockey Club is a dream come true. I was told to enjoy myself and I did."
Godolphin's Saint Baudolino claimed the runner-up spot in a bunch finish for the places.
Racing manager Simon Crisford said: "We are happy with that, it was a big effort. It was just a bit of a messy race, but we are delighted with the way he ran."
The British raiders failed to make their presence felt, with Brian Meehan's Most Improved (14th) and Ektihaam from the Roger Varian stable (15th) meeting all sorts of traffic problems.
John Gosden's Gregorian (18th) ran very wide round the home turn and the trainer feels the number of runners needs to be looked at.
He said: "He went to the chateau to check the opening times, I think! He went round Longchamp on the outside perfectly in the Poule d'Essai des Poulains.
"Twenty horses on that distance, there is too many hard luck stories. To run a pure race like the Prix du Jockey Club, there are too many hard luck stories. You wouldn't want to see a really nice horse get beaten for the wrong reasons when you are trying to find the best."
Jockey William Buick said: "It was a nightmare, it was a horrible race. He didn't handle the turn at all, he went straight on. It was a bit of a non-event."