Kentucky Derby third placegetter Gun Runner will miss the Preakness Stakes, leaving a likely field of 11 for the middle leg of the Triple Crown at Pimlico.

Gun Runner would have been the third choice in the Preakness.

His absence tightens the focus on Nyquist and Exaggerator, the top two finishers in the Derby who square off again on Saturday (Sunday AEST).

Trainer Steve Asmussen said Gun Runner, the Louisiana Derby winner, would remain at Churchill Downs.

"We plan on a serious summer of three-year-old races with him," Asmussen said.

"He's been in tremendous physical condition going into the Derby, and coming out of it, and we expect for him to continue to physically develop."

Nyquist, who took his record to eight wins from as many starts in the Derby, looms a short-priced favourite in the Preakness.

Exaggerator rallied from back in the Derby to finish 1-1/4 lengths behind Nyquist and should be a solid second choice.

Both Nyquist and Exaggerator had strong early morning gallops on Tuesday at Pimlico, finishing their work before rain moved into the area.

"We got to get on a nice track and no one got wet," Doug O'Neill, Nyquist's trainer, said.

In addition to Nyquist and Exaggerator, the probable Preakness field includes Abiding Star, Awesome Speed, Cherry Wine, Collected, Fellowship, Lani, Laoban, Stradivari and Uncle Lino.