Kentucky Derby winner California Chrome is shining even brighter as he heads into the Preakness Stakes, the second leg of US flat racing's elusive Triple Crown.

"I think he loves it," assistant trainer Alan Sherman said of the adulation the chestnut colt has received since arriving this week at the Pimlico racetrack in Baltimore.

The glow surrounding California Chrome dimmed just a little on Thursday when word went round he had been seen by a vet, but his connections quickly moved to dispel any concerns, saying the colt had a small blister in his throat that was not serious.

"He's fine," Sherman, the son and assistant to trainer Art Sherman said.

"It's not a big deal at all."

California Chrome's emphatic Kentucky Derby triumph on May 3 has made almost everything about him a big deal, and if the odds-on favourite wins on Saturday (Sunday AEST), things will only get bigger.

That would give him a chance to become the first horse since Affirmed in 1978 to sweep the coveted treble of the Kentucky Derby, Preakness and Belmont Stakes - with the final leg on June 7 at Belmont Park in New York.

"It's an awesome feeling having a horse of this calibre," Sherman said. "It's the first time we've had a horse this good, so we're enjoying the ride."

California Chrome comes complete with an appealing story of humble beginnings, bred by owners Steve Coburn and Perry Martin from an $8000 mare they matched for $2000 with an undistinguished stallion.

But after five victories in his past five starts by a combined 26 lengths, Coburn is not afraid to predict that California Chrome will be the first horse in 36 years to pull off the Triple Crown.