Nahoodh, ridden by Frankie Dettori, won the Group One Falmouth Stakes at Newmarket with a well-timed finish.
The 10-1 shot, having just her second run for Mark Johnston since leaving Mick Channon, flew up the hill to win by three-quarters of a length.
John Gosden's Infallible started well but could not match Nahoodh's pace and finished second ahead of pre-race favourite Heaven Sent and Seachange.
The stewards called an inquiry but the placings remained unaltered.
Johnston has had a relatively quiet season by his own high standards but was delighted with the display of his new arrival in the one-mile race.
He said: "We didn't decide tactics for today but we have been trying to get her to settle and relax.
"It was only two days ago we decided to run her over a mile again, and I did have her entered over six furlongs as well.
"We were looking for a seven-furlong race but the lure of a Group One was too much.
"She obviously gets a mile and there are richer pickings at that trip so she will probably stay at a mile."
Earlier, Please Sing, ridden by Eddie Creighton, won the Cherry Hinton Stakes while Art Princess was second and Ahla Wasahl third.
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