Young jockeys Keith and Erik Asmussen, both sons of Hall of Fame trainer Steve Asmussen, were each injured Saturday in separate races at Churchill Downs and Lone Star Park, respectively. Keith Asmussen was injured at about 12:47 p.m. ET in the 1st race at Churchill, a $10,000 claimer for fillies and mares three and up. The Equibase chart said his mount, Singsational (Audible) "was jostled between horses and squeezed back at the start, clipped a rival's hind heels and fell at the eleven sixteenths pole, then walked off." Singsational, who...