Sport: Misters Big

Every year, when spring rains start the bluegrass sprouting, some high-strung U.S. race horse suddenly gets the attention usually reserved for movie stars and .400 hitters. Servants cater to his whims, columnists dog his hoofsteps, and genealogists start excavating the deepest roots of his family tree. He has a name—in 1961 it was Carry Back, last year it was Ridan—but to railbirds he is always known simply as Mr. Big: the favorite for the Kentucky Derby.

This year there are two Misters Big—and for good reason. Harry Guggenheim's Never Bend and Rex Ellsworth's Candy...