The 139th Kentucky Derby Saturday will feature the world's fastest horses and biggest hats. The race, set to begin at about 6:20 p.m., is an all-day celebration of the "Most Exciting Two Minutes in Sports." Heavy rains are expected to slow the Churchill Downs track in Louisville. The favorites this year are Orb and Verrazano. Black Onyx, in the first post, was scratched due to injury, so only 19 horses will compete. Odds cited are those posted by oddsshark.com on May 1.