Caller One, the 5-year-old gelding who captured the Dubai Golden Shaheen (UAE-I) on World Cup Day earlier this year, fractured his right front sesamoid during a workout at Belmont Park on Tuesday, July 9, and will likely be retired from racing.The winner of 10 out of 20 lifetime starts and more than $3.1 million was preparing for a start Saturday in Calder Race Course's Smile Sprint Handicap when he changed leads suddenly on the track and pulled up."The only good thing was that it was better to have happened there than in a race when he could have hurt himself worse," said James Chapman, Sr., whose son James K. Chapman trained the gelding for the partnership of Theresa McArthur and Chapman Sr.'s wife, Carolyn, "We had a lot of nice things with him and were blessed to have had him."Caller One is by Phone Trick out of the Danzig mare Baltic Sea. He has 10 wins in 20 lifetime starts, including six stakes victories. Besides the Golden Shaheen win, highlights of Caller One's career included victories in the 2000 Kentucky Cup Sprint (gr. II) and Lafayette Stakes (gr. III) and in the 2001 Los Angeles Handicap (gr. III). He also competed in each of the past two Breeders' Cup Sprints (gr. I), finishing fourth in 2000 and third last year.While plans for Caller One's future were uncertain, Chapman indicated the injury was not life threatening, although it would probably preclude Caller One from returning to racing. "If he could come back he probably wouldn't be at the same level and I wouldn't want to do that to him," Chapman said.The gelding is expected to fly to Chapman's farm near Ocala, Fla. where a determination would be made whether surgery was necessary. "That's where he'll spend the rest of his days unless something miraculous happens," he said.