Country House was declared the victor of the 145th running of the Kentucky Derby at Churchill Downs on Saturday following "an inquiry ruling" and the disqualification of Maximum Security, officials said.
After the race, Prat filed a rider's objection claiming Maximum Security had impeded the path in the final turn. Country House and his jockey Flavien Prat then became the new winners and defied 65-1 odds.
Code of Honor was moved up to second and Tacitus - also trained by Mott - was third.
Maybe this was one for his father: Lookin At Lucky got saddled with the dreaded No. 1 post in the 2010 Derby, where he got pinned to the rail and wound up sixth.
A horse named Maximum Security was first named the victor of the 145th running.
Maximum Security was disqualified with officials saying he interfered, which means that long-shot Country House won the race.
North Korea sends a message with launch of short-range projectiles
Most recently, Kim held talks with Russian President Vladimir Putin for the first time in late April. Last month, North Korea said it had tested what it described as a new "tactical guided weapon".
"The horses between Country House and Maximum Security were affected", Prat said.
The only other time a Derby victor had been disqualified came in 1968, when Dancer's Image was taken down after a post-race drug screening announced several days after the race.
During Saturday's competition, Country House and the French-born jockey beat out 19 other competitors in the Churchill Downs race in Louisville.
After the post position draw, Omaha Beach was the early 4-1 favorite with jockey Mike Smith aboard, but scratched after an entrapped epiglottis made breathing hard for the morning line favorite. Koichi Tsunoda's long shot Master Fencer became the first Japan-bred horse to run in the Derby.
A pair of Bob Baffert entries, Improbable and Game Winner, came in fourth and fifth, respectively.
Country House will go for the second leg of the Triple Crown at the 144th Preakness Stakes on May 18 on NBC and the NBC Sports app.