Louisville, KY (Sports Network) - Mark Valeski, Louisiana Derby runner-up, will not start in Saturday's 138th Kentucky Derby at Churchill Downs. Trainer Larry Jones made the decision Tuesday morning.

Monday morning the colt had a five-furlong workout at Churchill Downs when he was timed in 1:00 1/5 and galloped out six-furlongs in 1:14 3/5.

The defection of Mark Valeski allows trainer D. Wayne Lukas to have Optimizer enter the Run for the Roses. Optimizer will be Lukas' 45th horse to start in the Kentucky Derby.

Optimizer finished 9th in the Arkansas Derby behind Bodemeister and was second to Secret Circle in the Rebel Stakes, both at Oaklawn Park.

05/01 12:03:04 ET