LOUISVILLE, Ky. — After 136 years, Apollo may rest in peace.

For generations, the 1882 Kentucky Derby champion had stood as the last horse to win the nation’s most coveted race without running as a 2-year-old. It was the longest standing curse in a sporting event rife with arcane rules and superstitions.

With so many contenders now coming to Churchill Downs on lightly raced foundations, trainers and handicappers had predicted Apollo was ripe to fall.

In the end, it took a massive chestnut with “freaky” athleticism to smash history. Pre-race favorite Justify won the 144th Derby on Saturday in just the fourth start of his undefeated career.

The favorite has won six straight Derbys.

Justify, with 5-2 odds, paid $7.80 to win. Good Magic, 9-1 at race time, finished second and paid $9.20 with Audible, at 7-1, closing fast for third and paying $5.80.

The trainer of Justify, Bob Baffert, earned his fifth Derby victory, one short of the record held by Ben Jones, and his first since American Pharoah won in 2015 on the way to the Triple Crown.

It’s too early to say if Justify has that kind of talent, but Baffert described him as a “superior” race horse, despite his inexperience. And 52-year-old jockey Mike Smith raved about the big colt’s ability to dial up a burst of speed on demand.

To pull off the Derby victory, he had to overcome not just the unfamiliar 1-mile distance but a 20-horse field rated by many the best in recent memory.

There was the Irish invader Mendelssohn, regarded as the best European-trained contender ever to shoot for the Derby. There were the four horses trained by Todd Pletcher, led by undefeated Magnum Moon and Florida Derby champion Audible. There was battle tested Bolt d’Oro, owned and trained by the upstart scaffolding baron, Mick Ruis, and Breeders’ Cup Juvenile champion Good Magic, saddled by the hottest trainer in the game, Chad Brown.

So many contenders with convincing pre-race arguments. And the mud added another element of uncertainty.

Derby day dawned wet and gray, with rain falling at varying intensity throughout the morning and afternoon. The track at Churchill Downs was still listed as fast through the first undercard races but was downgraded to sloppy by 3 p.m.