Trainer Steve Asmussen sent his GI Kentucky Derby and GI Kentucky Oaks hopefuls out to work at Churchill Downs Sunday morning. Winchell Thoroughbreds' Derby contender Epicenter (Not This Time) worked six furlongs in 1:12.20 (3/4), while Oaks hopeful Echo Zulu (Gun Runner) went the same distance in a bullet 1:11.80 (1/4). With exercise rider Wilson Fabian in the saddle, Echo Zulu broke to the inside of regular workmate King Ottoman (Curlin), who was ridden by former jockey Eddie Martin, Jr. Echo Zulu worked through eighth-mile fractions of :12.20, :23.80, :35.60...