Big Brown finished last at the Belmont Stakes in New York this weekend as Da'Tara came in a surprising first with odds of 38-1.
The winner of the Kentucky Derby and Preakness was expected to take horse racing's Triple Crown and started as favourite at Belmont, but fell well short of the mark.
Jockey Kent Desormeaux reported that the horse tired early after taking a comfortable third place early on in the race.
Desormeaux commented: "When I got outside going into the first turn, I said 'this is it. The race is over. I got it.' And unfortunately there were no popped tires. He was just out of gas."
Beyond simple tiredness, trainers were at a loss to explain the failure of the horse to take the final title to complete the triple.
The horse is the 11th to fall one short of the Triple Crown, the last winner being Affirmed who was ridden to the title by Steve Cauthen in 1978.
Big Brown finished last at the Belmont Stakes in New York this weekend as Da'Tara came in a surprising first with odds of 38-1.