Jockey Martin Dwyer celebrated his first British Classic win by guiding Casual Look to success in the Vodafone Oaks at Epsom on Friday.
Casual Look won by a neck
The victory also represented a major triumph for Andrew Balding, who is in only his first season as a trainer.
The 10-1 chance challenged fast and late on the outside to beat 10-3 favourite Yesterday by a neck, with 25-1 shot Summitville half a length away third.
Johnny Murtagh set what looked only a steady pace on Halawanda before Inchberry made a bold bid for glory.
But she was swamped inside the final furlong, Summitville taking a narrow lead only for Casual Look to get the better of her.
I dreamed about this for so long and I'm just so ecstatic
The unlucky horse of the race was Yesterday, who had difficulty finding a run until it was just too late.
Balding said: "I dreamed about this for so long and I'm just so ecstatic. I knew we had a good chance if she saw out the trip, and she did."
Dwyer, celebrating a 647-1 treble following wins earlier in the day on Aldora and Passing Glance, expressed his delight.
"That was unbelievable. I want to do it again. It went so fast. She's a good filly," he told BBC Sport.
"They went quick early on, steadied up and then from the hill they were quickening away. She travelled so well, and once she met the rising ground she really dug deep."
Winning owner Will Farish III, the American ambassador to Britain, said: "This is what we have been pointing for all winter.
The filly has trained well, Andrew has done a fabulous job with her and it's just a great feeling."
Balding saddled a 1-2 earlier in the afternoon when Passing Glance beat Highland Shot in the Vodafone Corporate Handicap.
And he made it a treble when Rimrod landed the Vodafone Surrey Stakes, the race after the Oaks.