On the Churchill Downs backstretch, leading up to the Kentucky Derby will be some of the brightest training stars in the sport: Bob Baffert, Jeff Mullins, Larry Jones, Jimmy Jerkens. And they’ll all have to make room for Tom ­McCarthy.

Such is the allure of the sport that a 75-year-old retired principal with a one-horse stable (a horse by the name of General Quarters), who won the Toyota Blue Grass Stakes on Saturday, could enter the sport’s most famous race with just as legitimate a shot at winning as the biggest names in the game.

“I think my horse is just as good as any of them,” said the thrilled McCarthy, a veteran though small-scale horseman who was a principal at three different Louisville public high schools before retiring in 1990.

It’s also the allure of this year’s Derby, which is quickly shaping up to be another directional delight, full of questions and intrigue.

From the west comes Baffert, the three-time Derby winner, back in the hunt for the roses after a two-year absence. Baffy’s bullet this time around is Pioneerof the Nile, the son of Empire Maker, who is on an impressive streak of wins covering the Robert B. Lewis, the San Felipe and the Santa Anita Derby.

One problem: Pioneerof the Nile has never run a race on the dirt, which happens to be the surface Churchill will use for the Derby for the 135th straight year.

From the east comes Mullins, the highly successful but sometimes controversial trainer who saddles Wood Memorial winner I Want Revenge. Saying I Want Revenge won the Wood is not giving the 3-year-old nearly enough credit. The son of Stephen Got Even got left at the gate at the start, then battled back through traffic to win the Grade I.

One problem: Mullins is in New York hot water for allegedly using an illegal medication called Air Power on another horse at Aqueduct the day of the Wood. He faces the New York Racing Association Backstretch Area Violations Panel on Thursday.

From the south comes Jerkens, the son of training legend Allen Jerkens. Out on his own for 10 years, after spending 20 years as an assistant to his father, Jerkens has Florida Derby and Fountain of Youth winner Quality Road.

One problem: Quality Road has been battling a bothersome quarter crack in his right hind hoof.

From the southwest comes Jones, who suffered Derby tragedy last year when his filly Eight Belles had to be put down immediately after finishing second in the 134th running of the Derby. Jones is back this time with Friesan Fire, who won the Louisiana Derby.

One problem: That race was way back on March 14th.

Now add McCarthy, who on Saturday recorded not his first stakes-race win, but his first Grade I win. Though he’s been in the sport off and on since the early 1960s, McCarthy has never had more than eight runners at a time. General Quarters is a $20,000 claimer that was coming off a troublesome fifth-place finish in the Tampa Bay Derby.

“This is like a Cinderella story,” Mike Adams, ­McCarthy’s son-in-law, said in the exuberant winner’s circle Saturday. “This is a guy that is not a big-time name. He just had a dream and a heart that’s huge.”

“I was always hoping,” said McCarthy. “I bred to Proud Clarion, and I bred to some nice horses. I always thought, ‘Is this the one? Is this the one?’ And they weren’t. But this is the one.”

It is one that has won both on the dirt at Tampa Bay Downs and now the Polytrack at Keeneland. It is also one that has trained, and trained well, over the same strip at Churchill Downs which he will be running on come May 2nd.

McCarthy will be competing against some of the same trainers who have been such a staple at the event.

“It’ll be an experience; it certainly will,” said ­McCarthy. “I’ve been looking at other people training good horses, and this time, thank God, I’ve got a good horse.”