Winsili, a 20-1 outsider, was a surprise winner of the Nassau Stakes at Glorious Goodwood.
Jockey William Buick held off Thistle Bird (33-1) and 5-1 chance Hot Snap to give trainer John Gosden back-to-back victories in the event.
There was a disappointing run from 7-4 favourite Sky Lantern, who was boxed in on the home straight as she struggled in her debut race beyond a mile.
Rex Imperator finished strongly to win the Stewards' Cup.
The 12-1 shot surged clear of Ajjaadd and Burwaaz in the closing stages of the six-furlong dash.
"This means a lot," Rex Imperator's jockey Neil Callan told Channel 4 Racing. "He jumped smart, (trainer) William (Haggas) said to ride your own race, to sit on him, wait for that burst and use him late.
"He's quickened like the Group One horse I thought he was."
"I had a good run through all the way, then I got behind the Godolphin runner (Sajjhaa) at the two-pole, I went to go round her but Mr Buick's filly rolled in on her and pushed her back on her heels," he told Channel 4 Racing.
"That's racing, she was very unlucky."
Winning Winsili rider Buick said: "I got a nice run through and she was very game. It's been an up and down week so it's nice to finish on a high.
"I had plenty of room in the straight and she travelled so well. I decided to take my time as she has a nice turn of foot."