The 50-1 outsider Qualify sprang a surprise to win an incident-packed Oaks at Epsom.
Qualify, ridden by Colm O'Donoghue for trainer Aidan O'Brien, beat favourite Legatissimo by a short head in a photo finish, with Lady Of Dubai third.
A stewards' inquiry was called after horses bumped into each other as the race unfolded, but the result stood.
Qualify came with a late burst to overhaul Ryan Moore on Legatissimo in the closing strides.
O'Donoghue, 34, said after his first British Classic victory: "Qualify has travelled, she is well balanced and I just wanted to keep her relaxed and come with that clean, straight run. It's the winning post that matters.
"I wanted to keep her on an even keel and keep her running. I didn't want anything interfering with her because we were on the outside of the track's camber. She has come home strong."
|The joint biggest-priced winner of the Oaks. Jet Ski Lady also won at 50-1 in 1991.|
|Bred by her Irish trainer Aidan O'Brien, who won the Oaks with Shahtoush (1998), Imagine (2001), Alexandrova (2006) and Was (2012).|
|Well beaten in two Classics earlier in the season - finishing last on her seasonal debut in the 1,000 Guineas at Newmarket and 10th in the Irish Guineas.|
|Bought last year by Spanish owner Chantal Regalado-Gonzalez.|
A bumper crowd in warm sunshine witnessed a dramatic running of the fillies' Classic.
It was a fifth win in the Oaks for O'Brien, but it came from the lesser fancied of his runners.
As the field entered the final furlong, several horses were bumped and Diamondsandrubies was badly hampered when Together Forever - ridden by O'Brien's son Joseph - collided with him.
Moore went clear on the 1,000 Guineas winner Legatissimo but looked stunned after Qualify went past him.
The winner was beaten seven lengths when finishing 10th behind victor Pleascach in her last run in the Irish Guineas.
There was no fairytale on Ladies' Day for Jessica Harrington, who was bidding to become the first woman to train the winner, with her horse Jack Naylor finishing out of the places.
Runner-up Legatissimo's trainer David Wachman said there were no excuses after the race.
"I'm delighted for Colm O'Donoghue as he deserves more big-race success," he said.