INGLEWOOD, Calif. -- Corey Nakatani, who was scheduled to ride in the Kentucky Derby on Saturday, sustained a "slight concussion" Thursday in a spill at Hollywood Park and will be sidelined until next week. The injury prevented Nakatani from riding Blue Burner in the Derby; he was replaced by Pat Day. Nakatani went down in the third race when his mount Whirlwind Trip clipped heels with Star Nine, the eventual winner ridden by Tyler Baze. Star Nine crossed over in front of Nakatani's mount at the half-mile marker of the 4 1/2-furlong race, causing Whirlwind Trip to stumble and unseat Nakatani.

Star Nine was disqualified from the win and placed last; Baze was handed a five-day suspension by track stewards for crossing over without sufficient clearance. Nakatani said Baze apologized to him after the race. When Nakatani's mount clipped heels, he was thrown off backward and landed on his feet. But the momentum caused him to fall backward and slam his head into the ground. Nakatani did not appear to be struck by any trailing horses, walked off under his own power, was examined at first aid, and later underwent X-rays taken at Arcadia Methodist Hospital.

On Friday morning, Nakatani's doctor advised him not to fly, and to take "two or three days off and play it by ear." The timing of the accident, two days before the Derby, could not have been worse. "I'm real disappointed, I was really excited about riding [Blue Burner]," Nakatani said Friday. "But it could have been worse."