The field for Saturday’s running of the Kentucky Derby is taking shape.The post position draw for the 137th Kentucky Derby is Wednesday. Up to 20 thoroughbreds will run the mile-and-a quarter course. Some of the top contenders include Florida Derby winner Dialed In, who could be named the early favorite on Wednesday. Uncle Mo was highly touted after winning the Breeders’ Cup Juvenile. Some jumped of his bandwagon after a third place finish in the Wood Memorial, but he could get the nod as the second favorite. There’s also Nehro, runner-up in the Arkansas and Louisiana Derbys.For handicappers who give weight to the jockey, Calvin Borel, winner of three of the past four Kentucky Derbys, will be aboard Twice the Appeal. He is expected to have relatively long odds despite Borel being in the irons.