* Tonalist wins Belmont in upset
* California Chrome finishes fourth to miss Triple Crown
Ridden by Mexican jockey Victor Espinoza, 4-4 favourite California Chrome moved into contention down the final stretch but could not catch the 9-1 chance Tonalist, ridden by Joel Rosario.
Commissioner, a 28-1 longshot, held on for second after leading until the final turn while Medal Count (24-1) took third.
California Chrome dead-heated with Wicked Strong for fourth, sending the huge crowd in New York into a stunned silence at the realisation that another Triple Crown attempt had failed.
After winning the Kentucky Derby and the Preakness Stakes last month, California Chrome was bidding to become just the 12th horse to achieve the feat - regarded as the ultimate challenge in American racing - and the first since Affirmed in 1978.
An unlikely champion who was bred by a factory worker and a scientist for just $10,500, California Chrome fairytale success story endeared him to millions of Americans who were instantly captivated by his rags to riches tale and thought he could be the one to break the Triple Crown drought.
Dubbed the Test of the Champion, the one and a half miles (2,400 metres) Belmont Stakes is the longest and most gruelling of the three races and has proven too much for most Triple Crown contenders.
Since Affirmed, 11 horses had started in the Belmont before Saturday with the chance to sweep the treble but all came up short. A 12th, I'll Have Another, was scratched from the final leg.