LOUISVILLE, Ky. — Todd Pletcher is throwing numbers at the Kentucky Derby again. Bob Baffert is seeking a fifth victory and he’s got the favorite, too. An old jinx could be disproved and history would be written if Mendelssohn wears the garland of red roses.

The 20-horse field for the 144th Run for the Roses on Saturday includes a handful of top contenders who have been consistent this spring.

Justify was the 7-2 favorite in early wagering Friday, but the southern California colt, trained by Baffert, is green with just three starts.

“We have a good enough horse that can win it but it’s a very competitive race,” Baffert said. “You’re going to have to have some luck.”

Justify is undefeated and Magnum Moon is 4-0, neither having run as a 2-year-old. They’ll be trying to upend a so-called curse: No horse since Apollo in 1882 has won without racing as a juvenile.

Magnum Moon, the Arkansas Derby winner, is one of the four horses to be saddled by Pletcher, who won last year’s Derby with Always Dreaming.

Pletcher’s Audible was the co-third choice at 6-1 with Mendelssohn on Friday. Along with Magnum Moon, Vino Rosso and Noble Indy were double-digit longshots for the trainer, who is tied with his mentor, D. Wayne Lukas, for the most Derby starters with 48.

Mendelssohn has the least amount of time on the Churchill Downs dirt. The Ireland-based colt made his first appearance Thursday, drawing attention with his screeching, after spending the first part of the week in quarantine for Aidan O’Brien. The trainer is 0 of 5 at the Derby, the biggest victory to elude him.

Mendelssohn was an 18½-length winner of the UAE Derby. His regal bloodlines and $3 million price tag suggest he would be a worthy champion, but no Europe-based horse has won the Derby.

My Boy Jack moved to the 5-1 second choice in early wagering. The closer is trained by Keith Desormeaux and ridden by Kent Desormeaux, a three-time Derby winner and Keith’s brother.

Despite Good Magic’s top credentials, he was relegated to the 7-1 fifth choice. He won the Breeders’ Cup Juvenile and claimed an Eclipse Award as last year’s 2-year-old champion. The colt won the Blue Grass last month, one of his six victories at six tracks.

Getting the ideal trip in the Derby is critical, especially with the traffic from 20 horses making a chaotic charge into the first turn. Jockeys want to avoid anything that would prevent their horse from getting into a rhythm, like being bumped, cut off or blocked.

“There’s so many horses in the field that seem like they have good chances to win the race with a clean trip,” said Chad Brown, who trains Good Magic. “I feel like we have one of them.”

Mick Ruis will try to become the third owner-trainer to win. He has Bolt d’Oro, the colt named in part for an Olympic champion sprinter, Usain Bolt. Bolt d’Oro finished second to Justify in the Santa Anita Derby.

“This is the best we’ve had him,” Ruis said.

The frequently changing forecast for Saturday calls for a chance of rain at different times during the day.