Hall of Fame trainer Bob Baffert was suspended by Churchill Downs after Kentucky Derby winner Medina Spirit failed a post-race drug test, and if the results are upheld, there’s a good chance that it will invalidate the victory.

Medina Spirit is Baffert’s fifth horse to fail a drug test in a year. The only horse to be disqualified for medication after winning the Kentucky Derby is Dancer’s Image in 1968.

Churchill Downs issued a statement yesterday saying Baffert won’t be able to enter horses at the track, and failure to comply with the rules and regulations puts the safety of the horses and jockeys at risk, and it can ruin the integrity of the sport as well.

“Churchill Downs will not tolerate it,” the statement said. “Given the seriousness of the alleged offense, Churchill Downs will immediately suspend Bob Baffert, the trainer of Medina Spirit, from entering any horses at Churchill Downs Racetrack. To be clear, if the findings are upheld, Medina Spirit’s results in the Kentucky Derby will be invalidated and Mandaloun will be declared the winner.”

Baffert announced the failed drug test, which he said he will fight “tooth and nail.” According to the trainer, Medina Spirit was found to have 21 picograms of the steroid betamethasone in a postrace sample, which is double the legal threshold in Kentucky racing.

Baffert said his camp was told of the positive test from Kentucky officials on Saturday. Medina Spirit has not been disqualified from the Kentucky Derby, but it can still happen after other tests are completed, per Baffert.

“This shouldn’t have happened,” Baffert said. “There’s a problem somewhere. It didn’t come from us.”

Medina Spirit won the Kentucky Derby on May 1 by a half-length over Mandaloun, giving Baffert his record-setting seventh victory in the race that starts the Triple Crown season.