Reve d’Essor, the Japanese 2-year-old filly champion who would have started as the short-priced favroite for next Sunday’s Japanese 1000 Guineas, will be sidelined for at least six months after suffering a leg fracture during a workout in the past week.Trained by Hiroyushi Moriyuki for Sunday Racing Co. Ltd., Reve d’Essor will undergo surgery at the Shadai Clinic on the northern Japanese island of Hokkaido, the center of the Japanese breeding industry.The fracture to the filly’s right foreleg is apparently not a serious one, giving hope for her future. By Agnes Tachyon out of 1 1/4-mile, Group 1 Prix Saint-Alary winner Reve d’Oscar, Reve d’Essor is undefeated in four career starts. She concluded her juvenile campaign with a victory in the Grade 1 Hanshin Fillies Mile and began her 3-year-old season on March 5 with a victory at the same track in the Grade 3 Tulip Sho. The Oka Sho, or Japanese 1000 Guineas, will be run at Hanshin on April 10.