Fort Larned made all of the running to win the Breeders' Cup Classic, the showpiece event of the two-day racing fiesta.
The Ian Wilkes-trained four-year-old showed laudable steel under birthday boy Brian Hernandez to deny Mucho Macho Man in a pulsating finish to America's richest race.
Mucho Macho Man seemed destined to win as he chased down Fort Larned along the straight, but Wilkes' colt would simply not be denied.
Flat Out finished some distance away in third, but last year's runner-up Game On Dude was very disappointing after having made a sloppy start.
Hernandez said: "Fort Larned has given me the greatest birthday present anyone could ever have.
"He's one of the best, and he showed it today."
Wilkes said: "I was looking for the wire at the end. Mucho Macho Man ran an unbelievable race, but Brian gave him a really good ride.
"If we missed the break we were done. This is the ultimate."
Bob Baffert said of the vanquished Game On Dude: "He broke half a step slow but he was right there.
"The winner's a good horse, but Dude just didn't show."