The Fugue bounced back from a disappointing run in Dubai to bound clear and win the Prince Of Wales's Stakes at Royal Ascot.
John Gosden's globetrotting mare, third to Al Kazeem in the race last year, travelled sweetly into the race and found plenty when asked to quicken by William Buick.
Well backed at 11/2, the five-year-old was held up in fifth as Alkaayed set the pace - as expected - for Mukhadram, but the front-runner was largely ignored and spent most of the first three-quarters of the race eight to 10 lengths clear.
He ran out of petrol coming into the straight and it was patently obvious The Fugue, who was injured when beaten in the Dubai Duty Free in March, was travelling better than the rest of her scrubbed-along rivals.
She produced when asked by Buick and went to the line a couple of lengths clear of Magician (6/1) and odds-on favourite Treve, who appeared ill at ease on much quicker ground than she had encountered when impressively winning the Prix de l'Arc de Triomphe last October.
Mukhadram came home close up in fourth with Dank proving a disappointment on her seasonal debut in a race that was run in a new course record time of 2:01.90, the ground firming up as the sun beat down.
Buick said: "She's been an absolute star for me and everybody back at the yard. She proved today what she can do against top-class horses.
"I must say a huge thank you to everyone back at Clarehaven for getting this filly here today. When she gets an uncomplicated run like she did today and they come back to her, she's lethal, like she was there. It means everything to everyone involved."
Gosden added: "This is great and the interesting thing about this race was that it was all about girl power, with Treve and this filly.
"It didn't work, the trip to Dubai (for the Dubai Duty Free). We trained her in the winter and she was like a little bud that went tight, but now she's flowered and she looks great.
"She got knocked over in the Oaks (two years ago), she got absolutely creamed and should have won, but she remains a very brave, lovely filly.
"She has superb owner-breeders, they don't have many in training and to have a filly of this quality, to beat the colts, is what it's all about.
"Treve is a wonderous filly and I would not want to take on Treve on soft ground over a mile and a half in the Arc - I wouldn't want to go near her, I think she's unbeatable.
"But today was summer racing, a mile and a quarter on good to firm ground, and that's the difference. You look at races like the Eclipse and the Juddmonte International and hope we have summer weather. She has little feet like a ballerina and doesn't like soft ground, so if it's soft we don't run."
The Fugue is owned and bred by Lord Andrew Lloyd Webber and his wife Lady Madeleine, who said: "We're so excited and she so deserves this. It hasn't gone her way sometimes and this is a very big stage to do it on.
"She's got her recognition as one of the best horses in Europe."
Her husband was witnessing The Fugue win in person for the first time, and he added: "We did genuinely think we were going to let her have a stroll round the park! We didn't believe she would do this, but it's the best day in our whole racing career."