Hall of Fame trainer Bob Baffert never dreamed he would win as many big races as he has since switching from quarter horses to thoroughbreds full-time in 1991.

Baffert, 70, started his thoroughbred operation with one horse. He wasn’t sure he’d make it. He was ultra-successful training the quarters, but the thoroughbred game was a whole different landscape.

“It was a big jump,” Baffert said during a phone interview this week. “I remember not being allowed to go to the box area because I didn’t have a box seat. I had to watch everything from the bottom level. It was a very humbling experience at first.”

Baffert was still winning major quarter-horse races and had 60 horses in his Los Alamitos barn when he decided to test the waters with thoroughbreds. It was a rocky beginning.

“First six months, first year, it was a little ugly,” he said. “If I hadn’t still had the quarter horses ... that was keeping me going.”

But it was also holding him back. D. Wayne Lukas, another Hall of Fame trainer who had enjoyed great success in the quarter-horse business before making the transition to thoroughbreds, offered Baffert some advice.

“We were talking in the paddock one day and he asked me, ‘Have you gotten rid of your quarters yet?’” Baffert recalled. “I said, ‘No, I’m having a hard time.’ And he said, ‘I was the same way. The minute I got rid of ’em my business doubled because they know you’re all in.’”

Bingo.

After winning three Cal Cup races in one day at Santa Anita in 1991, Baffert closed up shop that night on his quarter-horse operation and the rest is history.

On Sunday, he’ll try to extend his record number of victories in the $300,000 Grade I Del Mar Futurity to 17 when he sends out Best Pal Stakes winner Prince of Monaco and Mirahmadi in the 7-furlong test for 2-year-olds.

The best-known horse of his 16 winners is 2015 Triple Crown champion American Pharoah, tossed into stakes competition by Baffert after a fifth-place finish in his maiden special weight debut in 2014.

“It was pretty incredible,” he said. “He ran a horrible race first out ... but he worked really well, he drew the one hole and I was really debating whether to run him or not. I put him in at the last minute. I didn’t have a rider. Victor (Espinoza) picked up the mount. He was open, and he got the ride.

“I knew (when he won) he was really special, but they’ve all been pretty special. Most of them I expected to win. Some of them got beat. Roman Ruler (2004), he just got beat by a nose. It was a great race. There have been some disappointments, but all in all, it’s very satisfying.”

Satisfying to the tune of a record-tying six Kentucky Derby victories, two Triple Crowns, 18 Breeders’ Cup victories and four Eclipse Awards as the nation’s top trainer. All after he wasn’t sure he’d make it.

“I approached it day by day,” Baffert said. “I didn’t even know if I was going to be able to make the jump from the quarters to thoroughbreds. You surround yourself with the right people and you start having success. That’s how you gain owners, by seeing success. It took me a few years to figure it out.”

In addition to Prince of Monaco, Baffert has some other top juveniles in his barn. Heartland was an impressive winner his first time out and Muth, scratched from Sunday’s Hopeful Stakes at Saratoga, could make some noise down the road.

“I changed my mind on that (Muth),” he said. “He’s going to run in the American Pharoah at Santa Anita (Oct. 7).”

For the third consecutive year, Baffert will have to give his Derby-worthy horses to another trainer. Asked how badly it hurts, he chose not to comment.

“I really don’t wanna talk about that,” he said. “I don’t wanna go to that subject. We’re still dealing with that stuff. I don’t like to talk about it anymore.”

Follow Art Wilson on Twitter @Sham73