Frankie Dettori piloted odds-on favourite Enable to victory in the Prix de l'Arc de Triomphe for the second year in a row at ParisLongchamp.
The four-year-old filly is the first British-trained horse to win Europe's richest race twice.
Sea of Class came from a long way behind to finish second by a short neck, with Cloth of Stars third.
Enable, trained by John Gosden, becomes the eighth horse to win twice, while Dettori now has six Arc victories.
"It was my 30th Arc and I was more nervous than ever, not to mention excited, but in the race I found myself in a fantastic spot," said Dettori.
"It was almighty pressure on all of us - everybody wanted her to win and I had to get it right. It would be very naive to say that I wasn't nervous.
"What a genius John Gosden is, to win an Arc with that interrupted preparation."
Enable has missed much of the current campaign through injury following last year's win at temporary host venue Chantilly, but made an impressive comeback with victory at Kempton last month.
"It's not been the preparation we wanted, it has been very difficult, and we had a hiccup between Kempton and here with a slight temperature thing, so it has not been easy," trainer Gosden told ITV Racing.
"She was not at her best today. I have had a difficult year with her, it is entirely down to the filly and her guts and a lovely ride from Frankie.
"She has got the job done and it is down to her mind, she is a wonderful filly."
Gosden raised the possibility of Enable staying in training in a bid to become the first horse to win the Arc three times, although the final decision will be made by owner-breeder Prince Khalid Abdullah.
"It's great for Prince Khalid. He wanted to come here and if she's in good form there's no reason you wouldn't try to come again," added Gosden.
Gosden also said the owner will make the final decision as to whether Enable will be aimed at November's Breeders' Cup.
'The race of the year' - analysis
Cornelius Lysaght, BBC horse racing correspondent:
This was a fabulous success for a great horse-and-jockey combo, of course, but also a stunning triumph for John Gosden and team. They've nursed her back from injury, overcome an 11th-hour 'hiccup' when she briefly showed a temperature, and they have won Europe's greatest race off the back of the worst possible prep.
With such a prep it was a case not so much of not being at her best, but not being able to be at her best.
On top of everything else, Enable and the second produced the race of the year, a real thriller - poor Sea Of Class, if she hadn't had such a wide draw in the stalls…