Justify won the American Triple Crown and his connections were hoping to complete the Grand Slam of Thoroughbred racing by also winning the Classic.

[6] Good Magic, winner of the Haskell Invitational and the 2017 champion two-year-old, was also retired due to injury.

[7] The connections of another leading contender, Whitney Stakes winner Diversify, opted to bypass the Classic when his trainer, Rick Violette, became ill[8] and subsequently died.

Nineteen horses were pre-entered on October 24, though several of those had first preference in other races on the Breeders' Cup card.

The leading contenders included:[4][5][10][11] A poor start resulted in the horses with inside posts (Thunder Snow, Roaring Lion, Catholic Boy, Gunnevera) all being bumped and losing position.

[1][12] Accelerate's trainer John Sadler earned his first win at the Breeders' Cup in 45 attempts spread out over 30 years.

Accelerate won five Grade I races over the year, compared to four such wins for Justify.

Justify's wins included the American Triple Crown, while Accelerate became the first horse to win the Santa Anita Handicap, Gold Cup at Santa Anita, Pacific Classic and Awesome Again, in addition to the Breeders' Cup Classic.