King Guillermo, an Uncle Mo colt out of a Dixieland Band mare, spiked a fever Wednesday, did not train on Thursday morning, and was declared from the big race later in the day.

“A fever yesterday afternoon took us away from this great dream,” trainer Juan Carlos Avila wrote. “First it is the health of our King Guillermo, who will be ready to show that he is one of the best in the country sooner rather than later.”

King Guillermo had received high marks from some analysts for the way he had been training in preparation for the Derby. The colt was a $150,000 purchase as a two-year-old training by five-time Major League Baseball all-star Victor Martinez and still owned by him, in partnership.

King Guillermo broke his maiden at second asking and two races after that was a dominant winner of the Grade 3 Tampa Bay Derby — at odds of 49-1.

That was on March 7, and King Guillermo has made just one start since, a solid runner-up effort, behind Nadal, in the Grade 1 Arkansas Derby May 2.

Avila said that, health permitting, King Guillermo would head to Baltimore for the Preakness.

“I repeat later in the afternoon you will know why we had a great illusion of winning the best race in the world,” the trainer wrote. “Our next goal, having a healthy horse, will be the Preakness in Baltimore on October 3rd.“

With his scratch, there are now slated to be 17 Derby runners, with horses stalled outside the six-hole, where King Guillermo was to leave from, moving in one position. Tiz the Law is the 3-5 morning line favorite.