Leparoux had one of his best chances to win the Kentucky Derby in 2012 with the talented colt Union Rags but could only finish seventh after a troubled trip. Leparoux told the horse's trainer that he had heard a pop (indicative of a possible injury) with three-eighths of a mile remaining in the race, but no problem was found the day after. The trainer called the race a disaster and replaced Leparoux for the Belmont Stakes with John Velazquez. Union Rags won the Belmont but never raced again due to an injury to his suspensory ligament.