“He’s ready,” Baffert told him. “Ride him with confidence.”

When American Pharoah leaned back in the gate as the bell rang and the doors opened, the colt broke a step slow. Espinoza did not even worry. Within the first two jumps, American Pharoah had catapulted ahead of his seven rivals and glided into the first turn like a marble circling a roulette wheel.

“He was right in the lead where I wanted to be, in front of everybody,” Espinoza said.

Materiality gave chase for a mile, but American Pharoah picked up his tempo and shook that rival off at the mile.

“Steady, steady,” Espinoza said to himself.

Mubtaahij, from Dubai, took a run at him on the far turn, but got within only three lengths before peeling back. Revving up outside him, however, was the late-running Frosted. His jockey, Joel Rosario, scrubbed the gray colt’s neck and got within four, three and two and a half lengths, but then American Pharoah stretched his stride as if he were elastic and snapped off to a four-length lead. When Espinoza crossed the finish line five and a half lengths ahead, he finally allowed a smile to curl at the corner of his mouth and a raucous celebration to reverberate deep in his bones.

In the record books, it will say American Pharoah covered the marathon distance in 2 minutes 26.65 seconds, paid his backers $3.50 on a $2 bet and fattened his earnings to more than $4.5 million for his owner, Ahmed Zayat.

But as Espinoza galloped American Pharoah the length of the grandstand and let a thunderstruck crowd, many with tears in their eyes, cheer the ethereal performance of a once-in-a-lifetime athlete, he could barely catch his breath.

“Wow,” he told the outrider alongside him. “Wow. He’s just an amazing horse.”

Horse lovers and horse players alike have waited a long time to hear that.