The select yearling sale at Keeneland Race Course in Lexington, Ky., is where the world’s big players converge each year to throw staggering sums of money at thoroughbred racing dreams. Much of the most expensive horseflesh on the planet is paraded through a pavilion at the bucolic track in the Bluegrass region, with high rollers from the U.S., Europe, Asia and the Middle East silently signaling bids that can run well into seven figures. And it was at the Keeneland sale some 20 years ago that the world’s most aggressive equine purchaser probed the world’s hottest trainer on the question that was consuming him: “What does it take to win the Kentucky Derby?