A rematch expected to headline Saturday’s Preakness Stakes lost one of its combatants three days before post time.

Preakness favorite Muth was declared out of the race after his temperature spiked to 103 degrees upon his arrival in Baltimore on Tuesday evening.

“We are sick about this. The horse had been doing really well,” trainer Bob Baffert said. “But we have to do what’s right by the horse.”

He added that the 8-5 morning-line favorite was already feeling better Wednesday morning but will be sidelined as a precaution.

With Muth out, Kentucky Derby winner Mystik Dan will likely be favored in the second leg of the Triple Crown. He held off two rivals in a thrilling photo finish at Churchill Downs but was likely to become the first Derby champion since I’ll Have Another in 2012 not to go off as the favorite in the Preakness.

That was because Muth, barred from the Derby because Baffert is suspended from Churchill Downs, soundly defeated Mystik Dan in the March 30 Arkansas Derby. Given Muth’s consistency (never worse than second in six career starts), his trainer’s unmatched Preakness record and his five-week rest advantage over Mystik Dan, handicappers considered him an obvious favorite.

Mystik Dan’s trainer, Kenny McPeek, said he felt terrible for Baffert when he heard the news, though Muth’s exit will improve his chances to win a second Preakness.

“It’s a fragile game; it can happen to any of them,” McPeek said Wednesday as he made his way to Baltimore. “I guess it puts added pressure on us, but he’s ready,”

Baffert will still try to win a record-extending ninth Preakness with Imagination, a 6-1 co-third choice in the morning line. Fourth-place Derby finisher Catching Freedom is also a 6-1 choice.

Catching Freedom’s trainer, Brad Cox, wasn’t sure how much Muth’s absence might help his horse, a late charger who could have benefited if the morning-line favorite pushed a quick early pace.

“I shouldn’t say I feel their pain, but we’ve obviously been there and done that,” Cox said of the frustration associated with a late scratch. “I know the connections are going to make the right decision based on the horse. But Bob is still alive with another horse anyhow.”

That contender, Imagination, rested Wednesday morning and will take his first steps over the Pimlico track Thursday, a few hours before his trainer is expected to arrive in Baltimore.

Baffert said he’s “not giving up” on the possibility of taking the Preakness with the improving colt, who has two wins and four runner-up finishes in six career starts.

Both of Baffert’s horses arrived at Pimlico by van Tuesday evening after they flew from the trainer’s home base in Southern California to Newark, New Jersey — an 18-hour total trip.

“It’s a long trip, and I always worry about them getting sick,” Baffert said. “I have been so lucky; it just caught up to me. It was bad luck, bad timing. It’s disappointing because we were really looking forward to it. The timing is horrible, but the horse will be fine.”

Late scratches are unusual but hardly unprecedented in the Triple Crown races. One of last year’s top Preakness contenders, Brad Cox-trained First Mission, was scratched the day before the race because of a problem with his left hind ankle. Two weeks before that, Todd Pletcher-trained Forte was scratched the morning of the Derby, for which he was the early favorite. In 2012, I’ll Have Another was scratched because of tendinitis the day before he would have run for a Triple Crown in the Belmont Stakes.