Breeders` Cup winner Kalanisi retired Kalanisi, winner of last season`s Dubai Champion Stakes and the Breeders` Cup Turf, has been forced into retirement by an injury sustained during the Prince Of Wales`s Stakes at Royal Ascot.A hairline crack in his left foreleg has ended the racing career of the Aga Khan`s five-year-old son of Doyoun, and he will retire to his owner-breeder`s Gilltown Stud, County Kildare, Ireland.A stud fee has not yet been announced.The injury occurred as Kalanisi finished runner-up to Fantastic Light at the Royal meeting on his second outing since his valiant victory at Churchill Downs.The Aga Khan and trainer Sir Michael Stoute had hoped a month of box rest would cure the crack, but a slow rate of healing scuppered their plans to bring back Kalanisi for an end-of-season campaign.'We took the decision when X-rays showed that the speed of healing would make his end-of-season targets too difficult to meet, but there`s no doubt he was an exceptional horse and he should prove very attractive to breeders,' Pat Downes, manager at Gilltown, told the Racing Post.Stoute had called Kalanisi 'one of the best horses in the world' after he won the Turf, his first and only start in the United States.Stoute took over the colt from Luca Cumani for his four-year-old campaign last year that began with a narrow defeat at Windsor.Victory in the Queen Anne Stakes at Royal Ascot was followed by narrow defeats, both inflicted by Giant`s Causeway, in thrilling finishes in the Coral-Eclipse Stakes and Juddmonte International Stakes before Kalanisi beat Montjeu at Newmarket.In the Breeders` Cup Turf, Kalanisi swept past the best runners from North America to score by a half-length from Quiet Resolve.Johnny Murtagh, who rode Kalanisi at Newmarket and Churchill Downs, told the Racing Post: 'He was a very tough and durable horse who could produce a very serious turn of foot.'Kalanisi won six races in 11 starts, and finished second or third in the other five for Stg£1,373,088.