Big Brown’s surprise defeat in the Belmont Stakes was not related to injury according to trainer Rick Dutrow Jr.

But the trainer said connections of the US racehorse — tipped to take the third and final leg of the US Triple Crown last Saturday — are still at a loss as to what caused the 1-4 favourite to trail home an unexpected last.

Talking after the race, Mr Dutrow said Big Brown was not injured but that “something had got to be wrong” for the colt to have finished last.

More than 90,000 racegoers turned out on Saturday 7 June to see the three-year-old attempt to become the first horse in 30 years to win the American Triple Crown.

Big Brown arrived at Belmont Park in New York undefeated in five starts. Having won the first two legs of the US Triple Crown — the Kentucky Derby (3 May) and Preakness Stakes (17 May) with ease connections were confident for a win in the Belmont — the third and final leg of the Triple Crown.

But instead of a historic victory the Big Brown finished last, the first Triple Crown hopeful to do so.

And instead of being the first since Affirmed in 1978 to win the Triple Crown, he became the 11th horse since Affirmed to win the Kentucky Derby and Preakness Stakes but fall short in the Belmont.

During the race Big Brown was eased dramatically by jockey Kent Desormeaux round the home turn.

The 38-1 shot Za’Tara, ridden by Alan Garcia and trained by Nick Zito, won by five and a quarter lengths.

This was a second well-recorded win for Mr Zito in the race — four years ago his Smarty Jones foiled Birdcage’s attempt to win the Triple Crown by taking the Belmont.