Minnie Hauk beat stablemate Whirl to win the Oaks at Epsom in a one-two for Irish trainer Aidan O’Brien.
Ryan Moore just edged victory on the 9-2 chance, with previously unbeaten favourite Desert Flower in third.
It was an 11th win in the fillies’ race for Irishman O’Brien and a record-extending 46th British Classic.
“She’s a very exciting filly. She’s obviously learning and she’s going to improve with racing,” said the winning trainer.
O’Brien will saddle the Moore-ridden Delacroix, along with The Lion In Winter and Lambourn, in the Derby on Saturday as he also seeks an 11th victory in that contest.
In the Oaks, Desert Flower was one of the first runners under pressure as she seemed to struggle with the unique contours of the rollercoaster track.
The O’Brien pair pulled a long way clear but it took all of the final furlong for Cheshire Oaks winner Minnie Hauk, named after an American opera singer, to get on top.
She eventually passed long-time leader Whirl to triumph by a neck.
“Whirl came back and my filly found a little bit more. I think she’ll improve for the experience and as far as three-year-old fillies go, she’s very good,” said Moore after his fifth Oaks triumph.
Trainer Charlie Appleby said 1,000 Guineas winner Desert Flower looked a bit unbalanced coming down the hill and would be better on “a more conventional track”.
He intends to run Ruling Court in the Derby but warned the 2,000 Guineas victor’s participation would be in doubt if heavy rain arrived and made the ground testing.