The 2018 Kentucky Derby features favorite who must buck history to win

History says Kentucky Derby favorite Justify and his white-haired trainer Bob Baffert can’t win the 144th Run for the Roses Saturday, but who wants to bet on history?

Justify, the 7-2 favorite in early wagering Friday, has run just three races in his life and none as a 2-year-old.

No horse since Apollo in 1882 has won the Derby without racing as a juvenile. Since 1937, the 61 who have entered the Derby without a race under their belts by the age of 2 have all lost and only eight of the 61 finished in the money, The Wall Street Journal reports.

Baffert, a four-time Derby winner, came close to overcoming the so-called Apollo curse, finishing second with Bodemeister in 2012.

Kentucky Derby entrant Justify trains at Churchill Downs. His trainer Bob Baffert has won the Derby four times.

Kentucky Derby entrant Justify trains at Churchill Downs. His trainer Bob Baffert has won the Derby four times. (Reuters)

"We have a good enough horse that can win it, but it's a very competitive race," Baffert said of Justify. "You're going to have to have some luck."

The 20-horse field of 3-year-olds for this year’s Derby includes a handful of top contenders who have been consistent this spring.

The frequently changing forecast for Saturday calls for a chance of rain at different times during the day. Post time is 6:46 p.m. Eastern.

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

Trainer Todd Pletcher's Audible was the co-third choice at 6-1 with Mendelssohn on Friday. Pletcher is saddling four horses in the Derby. One of his other entrants is undefeated Magnum Moon who, like Justify, never raced as a 2-year-old. Pletcher won last year’s Derby with Always Dreaming.

Mendelssohn is a shipper from Ireland.

Mendelssohn was an 18 ½-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.

High school dropout Mick Ruis will try to become just the third owner-trainer to win. He has Bolt d'Oro, the colt named in part for 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 Associated Press contributed to this report.