Diego Velazquez won the Prix Jacques le Marois (G1) in a photo-finish Aug. 17, holding off a challenge from the fast-finishing Notable Speech.
The colt had been bought by Sam Sangster Bloodstock ahead of the race, with the expectation that he would stand at the National Stud following this season.
It was a first group 1 win for Aidan O'Brien's 4-year-old and the trainer's first victory in the Marois since Excelebration in 2012.
Diego Velazquez, ridden by Christophe Soumillon, stayed wide out of the stalls before settling behind The Lion In Winter and Dancing Gemini.
The Lion In Winter cut out the early running but faded badly in the final furlong, providing Charlie Appleby's Notable Speech with a late gap under William Buick. However, the line came too soon, with the winner holding on by a head.
O'Brien said: "He's always looked a smart horse. He had good 2- and 3-year-old form; he's determined. His last run was very good, and it's all come right in the last week or so.
"It's always incredible to have a horse running in Mr Sangster's colors, so I'm delighted for him."
On The Lion In Winter, he added: "He was a bit green; he wasn't sure of himself out in front."
The race is a 'win and you're in' for the Breeders' Cup, to which new owner Sam Sangster said: "That would be nice, but I'll leave plans to Aidan and the team at Ballydoyle. I'm just so over the moon."
Having donned the silks of Derrick Smith to multiple group successes at 2, 3, and 4, this was a first group 1 triumph for the Frankel colt. It was a timely update given it had recently been announced the 4-year-old will stand at the National Stud in 2026, after being purchased by Sam Sangster on behalf of a high-profile syndicate.
The National Stud's Joe Bradley said: "It's been an amazing day for everyone involved but especially Sam Sangster, who was the driving force behind this, and the syndicate people who came in behind him. It takes a lot of faith and bravery and that was rewarded today.
"We'll see what the rest of the year has to bring but we couldn't be more excited for the stud and everyone involved in it to have a horse like this retiring. A son of Frankel, a group 1 winner, it's incredible stuff."
An emotional Sangster added: "He is (fast for a Frankel). But you can see that, physically he's all there, he's all power and quite compact. Aidan said to me before the race his trip is a mile or a mile-one, so we knew he had that little bit of stamina up his sleeve. But he's quick, he's genuine, he's tough; he's a beauty.
"I'm very excited to be working with the team at the National Stud and I think he's going to get a phenomenal book of mares. You're surrounded by arguably the top stallions in Europe, with Frankel and Dubawi. So there is a fabulous pool of mares in the UK so hopefully he'll get a good bite at the cherry. He's beaten group 1 winners today and he's stamped himself one of the best in Europe, so it's very exciting."
Diego Velazquez cost a pretty penny at the sales, making a cool 2.4 million guineas to M.V. Magnier and White Birch Farm at Tattersalls Book 1 October Yearling Sale in 2022.
