At 23, the young man brought up in Louisiana's Cajun country has already compiled a skeleton of statistics that suggest his riding career will flesh out as one of the greatest of them all.
The champion apprentice of 1987, Desormeaux rode more winners than any other jockey two years later and this summer became the youngest rider to win 2,500 races.
After a quiet baptism in 1986 at Evangeline Downs, Desormeaux moved out of Louisiana to Maryland, where the touchpaper was lit on his journey. In his record freshman year his mounts won dollars 5.1m and his 20 Stakes victories overtook the mark of another young achiever better known to British audiences, Steve Cauthen.
Three years ago, Desormeaux moved again, to the even more demanding forum of riding in California. 'It's been tough, to say the least,' he admits. 'As far as Maryland was concerned I didn't have to work very hard. Just showed up and rode my tail off. Now I have got to work my tail off (in the mornings) and ride my tail off (in the afternoons).'
Yet last December the shoots of a brilliant future were almost ripped up in a maiden-claimer at Hollywood Park. Desormeaux was thrown by a veering frontrunner under a pack of horses, sustaining more than a dozen hairline fractures to his head, two haemorrhages and a swelling on his brain.
His face, whose boyishness framed under dark hair is betrayed only occasionally by light stubble, was so disfigured that his wife failed to recognise him. Desormeaux himself failed to recognise his sport when he returned.
'When I got into the saddle for the first time it felt like a new chair,' he says. 'It was like someone had adjusted my recliner and the leg rest was in a different place. It was weird.'
Not weird enough to stop the jockey winning on his first ride back, though, and he attempts another first this afternoon when he goes for an initial Breeders' Cup victory after seven losing rides. 'This meeting is as prestigious and pride-worthy as the Kentucky Derby,' he says. 'I don't know why, but I feel confident about this year. Something tells me I might win one.'
A measure of Desormeaux's ascent is that he sits out just one race this afternoon, the Juvenile Fillies, and he has promising rides, not least on the talented but unpredictable Toussaud. Bobby Frankel's filly, who ran in Britain last year for John Gosden, will take up to 20 minutes to get to post for the Mile.
'She freezes, she spins, she wheels, she does everything she can not to go to the gate,' Desormeaux says. 'Until the guy (assistant starter) gets behind her with the buggywhip, then she stops refusing and goes right into the gate.
'Then I have to deal with her racing antics. She's bolted with me, ducked in with me and she stops on a dime if she gets to the front too soon. I have to ride her accordingly.'
But it is on Kotashaan, another ex-European horse, who was formerly trained in France by Criquette Head, that many expect him to break his Breeders' Cup duck. The winner of the Oak Tree Invitational Stakes at this course last month is trained by Richard Mandella, one of the deep ranks of Desormeaux admirers.
'Kent's a personable kind of guy with a good personality, and he has the qualities all top jockeys need,' the trainer says. 'He is athletic, has natural horse sense and a lot of courage.
'I'm not a great believer in one man being that much better than another in the top category, but you couldn't name a jockey better than him. I place him as high as anyone. I'm sure it's highly likely that one day the figures will show he's been one of the greatest.'