LOUISVILLE, Ky. — Falling Sky has been plenty frisky in his gallops at Churchill Downs, a sign the speedy colt could be a major factor in setting the early pace in the Kentucky Derby. Whether he has the stamina to last 1 1/4 miles is a question to be answered Saturday.“He was really into it,” trainer John Terranova said after Falling Sky’s gallop. “He’s always into it.”Falling Sky is 3 for 6, with his wins coming as a front-runner. He was the leader in the Arkansas Derby turning for home before finishing fourth.In a Derby with few confirmed speed horses, Falling Sky should be easy to spot early on. Look toward the front of the 20-horse field.“I’d just like to see him comfortable wherever he’s going to be, whether it’s on the lead or close,” Terranova said. “Knowing him, he’s going to be forwardly placed. There’s no getting around that fact.”Full fieldThe one empty spot in the Derby created a scramble, with Giant Finish unexpectedly landing in the race.After several horses were withdrawn a day earlier, the field shrank to 19, one under the limit. The open slot did not last long. Fear the Kitten joined the lineup, bringing the Derby up to a full complement.On Tuesday, the owner of Giant Finish decided he wanted in, and his horse had enough points to surpass Fear the Kitten under the new system this year that determines Derby eligibility.Derby DayThe forecast calls for a 40 percent chance of rain with temperatures topping out in the mid-60s. NBC Sports will present 14 1/2 hours of coverage, starting Wednesday. NBC will take over with three hours of live coverage Saturday starting at 3 p.m.