Fleur Forsyte turned in a career best-performance in the British EBF & Sir Henry Cecil Galtres Stakes at York.
Despite bringing just a Salisbury maiden win to the table, the James Fanshawe-trained three-year-old took a significant step forward to take top honours in the Listed contest.
Much of the focus centred on Ribblesdale runner-up Mori but she was soon sending out distress signals, with Ryan Moore calling for her maximum effort early down the home straight.
Although looking a shade green late on, Fleur Forsyte (12-1) stayed on well enough for pressure to keep More Mischief, who was giving the winner almost a stone, at bay by two and a quarter lengths.
Fanshawe said: "She was in front a while. I've always really liked her. She got a bit upset at Newbury so we put a hood on her and she finished third in the Chalice Stakes.
"She worked very well last week, but that is easy to say now she has won.
"She is in at Ascot on Champions Day and the Prix de Royallieu. It is great to win Henry's race and he was always a help on the (Newmarket) Heath."