Pyro, winner of the Louisiana Derby, appeared headed for a favorite's role at the Kentucky Derby until struggling to finish 10th Saturday.
Cowboy Cal had the lead heading into the stretch and engaged in a tremendous duel with Monba before jockey Edgar Prado inched his mount ahead in the closing strides.
Kentucky Bear rallied to finish third.
Monba was coming off a 12th-place finish in the Fountain of Youth Stakes.
In another Kentucky Derby prep race Saturday, Gayego captured the Arkansas Derby. Sent off as the 2-1 favorite, Gayego defeated Z Fortune by three-quarters of a length.