Circular Quay, Tampa Bay Derby winner Street Sense, Great Hunter and Blue Grass winner Dominican are set to run in the Derby off just two prep races. Tradition calls for at least three.

The last Derby winner with two preps as a 3-year-old was Sunny’s Halo in 1983; before that it was Jet Pilot in 1947.

For the first time, some of this year’s potential Derby trainers are working their horses on synthetic surfaces, even though the Run for the Roses is on traditional dirt.

Four of Pletcher’s five candidates, along with Doug O’Neill’s trio of Great Hunter, Liquidity and Cobalt Blue, will complete their pre-race workouts on Keeneland’s artificial surface made of wax-coated sand, synthetic fibers and recycled rubber.

Pletcher won’t head to Louisville until Tuesday, although he sent Sam P. ahead so the excitable colt could get used to the atmosphere.

“We’re still trying to adjust and learn more about it,” Pletcher said of the new surface.

If it’s rainy, and it often is during Derby week, horses don’t need to wait for synthetic surfaces to dry out as they do with dirt, allowing for extra training time.

Curlin and stablemate Zanjero turned in impressive workouts at Keeneland, and critics will be comparing those with their pre-Derby trips over Churchill’s dirt.

Carl Nafzger, who won the 1990 Derby with Unbridled and trains Street Sense at Churchill, believes it’s too early to know how the transition from synthetic to dirt will affect the Derby.

“I suppose if some horse is trained on it wins (the Derby), they’ll all say, ‘Oh, big deal,”’ he said. “But if I win it, they’ll say, ‘Well, see, they shouldn’t have trained on Polytrack, they should have been at Churchill.”’

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