Gun Runner, third-place finisher in the Kentucky Derby, will skip the Preakness, leaving a likely field of 11 for the middle leg of the Triple Crown on Saturday at Pimlico.
Preakness post positions will be drawn Wednesday evening.
Trainer Steve Asmussen said Gun Runner, the Louisiana Derby winner, would remain at Churchill Downs.
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"We plan on a serious summer of 3-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."
Gun Runner figured to be the third choice in the Preakness wagering. His absence tightens the focus on Nyquist and Exaggerator, the top two finishers in the Derby who square off again in the Preakness.
Nyquist, 8 for 8 following the 1¼-length Derby victory, looms a short-priced favorite in the Preakness.
Exaggerator rallied from 15th to be second in the Derby and should be a solid second choice on the morning line.
Both Nyquist and Exaggerator had strong early morning gallops Tuesday at Pimlico, finishing up before rain showers 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.