Kastoria, the only distaffer in the field, roared past heavy favorite Yeats in the final 50 yards to claim victory in the Irish Field St. Leger (Ire-I) at the Curragh on Saturday.Benefiting from a patient ride from jockey Mick Kinane, Kastoria tracked the leaders from fourth throughout the early stages of the race. In the meantime, Yeats and jockey Kieren Fallon were settled into second, just off the pacesetting Percussionist. With five furlongs left to run in the 1 ¾ -mile marathon, Fallon said 'go', and the son of Sadler's Wells responded to immediately take the lead.Yeats appeared to be home free, but Kastoria would not be denied as she collared the Ascot Gold Cup (Eng-I) victor to win by ½-length. The Whistling Teal was 10 lengths further back in third.Kastoria, a 5-year-old chestnut mare by Selkirk out of Kassana, by Shernazar, races for her breeder, The Aga Khan. She hails from the female family of champion Kahyasi, winner of the Ever Ready Derby (Eng-I) and Budweiser Irish Derby (Ire-I) in 1988.John Oxx, who trains the mare for The Aga Khan, indicated that her next start might be in the Canadian International Stakes (Can-IT) on October 22.