Luca Cumani's Silk Sari absolutely bolted up in Doncaster's DFS Park Hill Stakes.
Joint-owned and bred by Fittocks Stud, managed by the trainer's wife, Sara, she went off at 8-1 for what is known as the fillies' St Leger after landing a Listed event at Newbury in early August.
Cascading set the pace for much of the way but Silk Sari was cruising in the home straight and quickened five lengths away from Groovejet.
It was Cumani's fifth winner of the Group Two, and he said: "I must say I'm surprised. I thought she would run well - she's been in excellent form - but winning like that was unexpected.
"There's a mile and five Group race (Prix de Royallieu) on Arc weekend for fillies, she might go for that.
"She's been great for the family, it's a great success. After that she's going to Dubawi, the bloodlines will suit, as well as attitudes and racing style."
Jockey Andrea Atzeni said: "She travelled beautifully in behind. They went a nice gallop which suited her. I thought she'd run well but I didn't think she'd win that well."
Criteria was third for John Gosden, who said: "She had no excuses. She stays well and she's very genuine. I think she'll be a better filly next year."
Seal Of Approval had fallen in the same race 12 months ago before going on to Group One glory in the Qipco British Champions Fillies & Mares Stakes.
This time she was fourth, and trainer James Fanshawe said: "She excels when the ground is really soft and is able to quicken. The ground in the straight was probably just a bit too quick for her. The aim is to go back to Ascot for the race that she won last year."
Cumani and Atzeni combined for a double as 7-2 chance Blue Waltz danced clear in the One Call Insurance Thoroughbred Breeders' Association Fillies' Handicap.
The Newmarket handler said: "This is just a step on her way to better things, at least that's what I hope.
"She may run again this year, but she will not be suited by soft, when it comes, so we'll see. She will stay in training next year."
