Missunited (3/1 favourite) put up a brave performance to see off all-comers and land the Sterling Insurance Lillie Langtry Stakes.
Michael Winters' admirable mare was rewarded for her fine third in the Ascot Gold Cup to land this Group Three prize 12 months on from her triumph in the Galway Hurdle.
Jim Crowley always had the seven-year-old up with the pace set by Nymphea before settling sailing for home fully three furlongs from home.
The challengers came thick and fast in the closing stages but she would not be denied and kept on with gritty determination to win by half a length from Arabian Comet, with Waila just a head away.
Missunited was dismounted on the racecourse by Crowley, who said: "She pulled up a bit sore but is walking better now.
"She's unbelievably tough - one of the toughest horses I've ever ridden - but she was probably just feeling the ground there.
"She battled so well, she was never going to be passed.
"Fingers crossed she's OK."
Winters said Missunited is now likely to be retired.
He said: "I'd say that could be her finale now, we've seen the best from her.
"If you had a choice to finish up here, I think you'd pick it.
"She ran her heart out all the way to the line. It's fabulous and I suppose she's a horse of a lifetime.
"She is known by everyone in the National Hunt scene and now she's done it on the Flat as well.
"I'm not looking forward to putting her in foal, but her owners probably are."
Missunited was later found to have damaged a suspensory ligament in a leg.
She retires as winner of 12 races on the Flat and under NH rules, including the Galway Hurdle, one of Ireland's most famous handicaps, a year to the day before her Goodwood victory. She earned some £386,000.