It could have been a day in which American racing received a much-needed boost.
Instead, Big Brown finished last and, in doing so, gave rise to an uncomfortable question about his form.
What part did drugs play?
Big Brown fought out a good win in the Kentucky Derby. He was the runaway winner in the Preakness Stakes and headed into the Belmont unbeaten in his five previous starts.
No one can deny that every athlete - equine or otherwise - can have an off day. Perhaps that played a part in the Belmont. Perhaps its was the 30deg C heat on the course. There was also concern over a cracked hoof but Big Brown showed no evidence of lameness. Apart from that, there was nothing to indicate such a spectacular slump in form.
And spectacular it was. Big Brown was handy enough to the final turn but had nothing left. Jockey Kent Desormeaux says Big Brown is the best horse he has ridden but was at a loss to explain his mount's lack of finish.
"I had no horse," he told reporters.
The form slump was such that racegoers must now be asking what part the anabolic steroid Winstrol may have played in Big Brown's loss.
Trainer Rick Dutrow has admitted to regularly dosing Big Brown with Winstrol, also known as Stanozolol, which can build muscle mass and speed healing.
It's nothing Dutrow needs to keep secret. Its use is legal in 28 of the 38 states that have horse racing. The 10 racing states with bans do allow it, but only if prescribed for a medical condition.
The states in which the Triple Crown is raced are unaffected by the bans.
Dutrow told the media that all the horses he trains receive Winstrol on the 15th of each month. However, he said he had not given Big Brown a shot since before the Kentucky Derby and told reporters he would not receive one before the Belmont.
And so the question arises. It might not have been the heat. It might not have simply been an off-day. Perhaps Big Brown's form slump can be explained by the withdrawal - temporary or otherwise - of Winstrol.
It is not the sort of controversy American racing needs. There are already major issues doing real damage to the sport. The safety of track surfaces, the durability of thoroughbreds, the use of whips, even the age at which horses take to the track.
Animal welfare groups have been focusing on the sport for all these reasons.
But perhaps the most damning is the industry's policy towards steroid use. It is unacceptable in human athletes, so why should it be acceptable in racehorses in a majority of US states where there is racing?
Given the very specific worries over racing - the durability of horses and the high profile deaths of fine horses like Barbaro and Eight Belles - you would think a total ban on steroid use would be a no-brainer.
But not yet.
There is a groundswell of support within the US industry for a ban. Until that time, it's hard to believe the industry is genuinely concerned about any of the key safety issues that continues to erode support for the sport by the day.