The drought looms larger every spring for a sport seeking a superstar to offset attendance declines and doping scandals.
Hopes invariably rise anew on the first Saturday in May in Louisville. And this year will be no different as another packed field of 20 lines up to run the 140th Kentucky Derby.
After a prep season during which several would-be contenders fell by the wayside because of injuries or flat performances, California Chrome emerged as a consensus favorite. Without an obvious No. 2 choice, the spotlight will shine on the California colt and his veteran trainer, Art Sherman.
But after months of surprising results in the biggest prep races, another upset would hardly be an upset at all. Such is the nature of the Kentucky Derby, with so many horses on the track and so few tested against the best competition.
As the field for Saturday's race shapes up, here are five storylines to watch:
Will California Chrome be the sport's next star?
He's certainly off to the right kind of start. There was already talk of Chrome as a possible Kentucky Derby favorite before he lined up in the Santa Anita Derby three weeks ago. He left no doubts, blowing away a field that included fellow Derby contenders Hoppertunity and Candy Boy.
He's an attractive, personable colt, apparently as comfortable around people as he is around other animals. His owners, Steve Coburn and Perry Martin, are middle-class folks without a long history in the sport. His trainer has been in the game more than 60 years but has never saddled a Derby winner.
It has the makings of a great story.
Now all California Chrome has to do is win. Handicappers like his chances, noting his ability to run near the front of a fast pack and keep churning as the speed horses fade.
If not Chrome, then who?
The field of challengers has thinned. Constitution, so impressive in winning the Florida Derby, was scratched because of a shin injury. Cairo Prince, who received early praise as a potential Derby favorite, was scratched because of an ankle injury.
None of the remaining threats to California Chrome brings an unblemished resume.
Wicked Strong is probably the most common No. 2 choice after an impressive win in the Wood Memorial. But he ran poorly in Florida earlier in the spring, leading some to question his chances outside his home base of New York.
Handicappers also remain high on Bob Baffert's Hoppertunity, who lost to Chrome at Santa Anita but wasn't really pushed to catch him after getting stuck in early traffic. Hoppertunity has run five times this year after not running as a 2-year-old, so he's battle-tested.
Samraat and Vicar's in Trouble have had solid results but are considered lesser physical talents. Intense Holiday and Candy Boy had handicappers excited only to disappoint in their final prep races.
Are there any appealing underdogs?
Danza might not be a big underdog come race day, but he's a great underdog story.
The Todd Pletcher colt started as a 41-1 afterthought in the Arkansas Derby only to demolish a field that included fellow Derby contenders Ride on Curlin, Bayern and Tapiture. Danza had run only once before in 2014, finishing third, so he truly came out of nowhere to thrust himself into the pack of Derby hopefuls.
Among trainers, a familiar name or an upstart?
This year's race will feature an intriguing blend of trainers, from the usual suspects such as Pletcher and Baffert to lesser-known veterans such as the 77-year-old Sherman and Jimmy Jerkens, who will saddle Wicked Strong.
Pletcher, a six-time Eclipse winner as the sport's top trainer and again the leading money winner this year, could saddle as many as three horses in the Derby, which he has won just once. Baffert, who has won the Derby three times, also could start as many as three, depending on how the bottom of the field shakes out.
Sherman and Jerkens have carved out excellent careers in California and New York, respectively, without regularly reaching the Triple Crown stage. Sherman, in fact, hasn't been involved with the Derby since 1955, when he went to Louisville as an exercise rider for the great Swaps. If he wins after 59 years away, he'll be just as popular a story as California Chrome.
Will off-track controversy overshadow the race?
Racing fans are used to doping scandals and reports of thoroughbred deaths, but the sport's troubles deepened in March, when People for the Ethical Treatment of Animals released undercover videos of disturbing practices in the barn of top trainer Steve Asmussen.
PETA filed state and federal animal-cruelty complaints against Asmussen and his assistant Scott Blasi, alleging that they encouraged a jockey to shock horses with an electric buzzer, among other offenses. The complaints, revealed in a New York Times report, also named figures such as trainer D.Wayne Lukas and jockey Gary Stevens.
Asmussen is under investigation in New York and Kentucky. He fired Blasi and saw his name removed from this year's Hall of Fame ballot. He is sure to be a topic in Louisville, where he's expected to saddle Tapiture for the Derby.
The 140th Kentucky Derby
Post time: About 6:25 p.m.
Triple Crown races
Kentucky Derby: Saturday
Preakness: May 17
Belmont Stakes: June 7
TV: All on chs. 11, 4