Favourite American Pharoah won the Kentucky Derby to give jockey Victor Espinoza back-to-back wins in the race before a record crowd of 170,513.
The Bob Baffert-trained horse had won four times on the trot coming into the 'Run for the Roses' at Churchill Downs.
American Pharaoh went to the front just past the final turn and finished ahead of Firing Line, trained by Englishman Simon Callaghan.
Another Baffert-trained horse, Dortmund, finished third.
|The US Triple Crown|
|American Pharoah will now set his sights on the second leg of the US Triple Crown, the Preakness Stakes at Pimlico on 16 May, before the Belmont Stakes on 6 June|
|Only 11 horses in history have landed all three races in the same season, with the last to win it being Affirmed in 1978|
The winner has an unusually short tail after another horse chewed the end of it off on the farm.
Espinoza, who as a teenager worked as a bus driver in Mexico City to pay for jockey school, won the 2014 race on California Chrome.
"I feel like the luckiest Mexican on Earth," said the 42-year-old moments after crossing the finish line.
"I was growing up and all I wanted to be was successful and I chose to be a jockey,"