Castle Lady overcame inexperience to step up with panache and land the Group Three Prix de la Grotte at ParisLongchamp.
The fillies had their Guineas trial and nine went to post for this race over a mile.
The race got underway with Imperial Charm among the early leaders, with Castle Lady.
Setting down, it was Imperial Charm who led, with Epistrophy joining her to the outside and then Sicilia next to the rails and Castle Lady.
Into the home straight, Imperial Charm held the call under Andrea Atzeni, who set sail for home, but was challenged by Castle Lady and Epistrophy.
Castle Lady and Mickael Barzalona came with a sustained challenge down the outside and gradually wore down the long-time leader.
At the line, Castle Lady was about 1 ½ lengths clear of Imperial Charm and then came Epistrophy.
The Henri-Alex Pantall trained Castle Lady is a daughter of Shamardal, who only made her racecourse debut in mid-March.