Sandrine was a decisive winner of the Albany Stakes, opening race on day four at Royal Ascot.
David Probert brought Andrew Balding's filly with a telling challenge in the last two furlongs, passing long-time leader and eventual runner-up Hello You to win by a length and a half at 16-1.
Sandrine, an all-weather winner at Kempton last month, remained unbeaten and proved she is hugely adaptable as she made light of testing conditions after torrential rain which had put the card in doubt until barely an hour before the first race.
Oscula finished third, just half a length further back, having ploughed a near lone furrow up the stands side.
Probert said: "She was super fit and hardy for an inexperienced filly, and quite relaxed in the early stages which helped her for the finish.
"We had such a deluge, the ground is loose and they are galloping through it."
Balding won the Coventry Stakes on Tuesday with Berkshire Shadow.
The Kingslcere trainer said: "I felt it was sure to be off driving here - we were only coming because we were having lunch, I thought it was certain to be abandoned!
"But I'm so pleased for Kirsten and all the team at Lanwades who are great supporters, she thoroughly deserves a win like this.
"She was impressive when she won, we thought it was a low-class race at Kempton, but the form worked out well.
"She worked well last week and we felt we were entitled to run. We were a bit concerned about the ground because there were mixed messages in the pedigree, but Kirsten told me Bobby's Kitten only raced in Ireland on soft ground, so it was worth a go and David gave her a beautiful ride.
"She did it nicely today, there was no fluke about it. She travelled liked the best horse in the race and I thought she was impressive."
Of Hello You, trainer Ralph Beckett said: "She hit the boxes and was quite free, but she saw it out well.
"Her programme will speak for itself with the likes of the Cherry Hinton and the Lowther amongst possible targets."