Once, he was the horse to beat . Now, Nyquist will not run in the Belmont Stakes, CNBC has learned.

Mario Gutierrez, aboard Nyquist #3, reacts after losing to Exaggerator #5, placing third during the 141st running of the Preakness Stakes

Nyquist trainer Doug O'Neill confirmed that the thoroughbred will not run "due to being sick." Following the Preakness Stakes, where the horse finished third, Nyquist was hit by a fever.



On Monday, O'Neill posted on his Facebook page that his racing team delayed shipping Nyquist to New York after the Derby winner had an elevated temperature. He had said the team, Reddam Racing, owned by Paul Reddam, was awaiting blood tests.

The horse has an elevated white cell count and would be treated with stronger antibiotics, a spokesman said.

The Belmont is June 6. Since the Derby and the Preakness were won by different horses, no Triple Crown is at stake this year.