Hopportunity, the second favourite for the Kentucky Derby, is out of the race.
Trainer Bob Baffert says the colt has a sore left front foot. Hopportunity was the 6-1 choice for Saturday's race and was to have been ridden by Mike Smith.
The scratching on Thursday means Pablo Del Monte can run in the Derby. However, the 50-1 shot would have to start from the No. 20 post position, instead of Hopportunity's No.11 post.
It wasn't immediately known if Pablo Del Monte's owners would want to start under that condition.
Baffert says Hopportunity's foot problem was discovered on Wednesday.
Baffert has another horse in the race, 20-1 shot Chitu.