Kentucky Derby winner American Pharoah and stablemate Dortmund have stretched their legs at Pimlico for the first time in preparation for the Preakness Stakes.

The two colts trained by Bob Baffert were flown in from Louisville, Kentucky, to Baltimore on Wednesday afternoon.

Both went out for a morning gallop on a pleasantly cool and sunny morning on Thursday (Friday AEST).

Dortmund, third in the Derby, was the first on the track and looked fresh and fit as he focused on a tour of the oval.

American Pharoah followed right behind, gliding over the surface in his usual nimble fashion.

"This cold air really puts these horses on their toes," Baffert, a five-time Preakness winning trainer, said.

"They were happy to get out. They just marched up to the racetrack, eager to get to work. You don't want to lead them up there like a borrowed dog. They looked healthy, bright, in top condition."

If that good form holds, it could be a very predictable Preakness.

American Pharoah is the 4-5 favourite, with Derby third Dortmund the 7-2 second choice.

"My job is to get the saddle on them so they don't get stirred up," Baffert said. "We can only fine tune them. We only have a couple of days."

The Baltimore weather forecast is unsettled for for the race on Saturday (Sunday AEST) with thunderstorms possible in the afternoon.