California Chrome's Triple Crown dream ended in heartbreak at Belmont with owner Steve Coburn criticising the winner's connections for not running in the first two legs.

Coburn's beloved Chrome, the unlikely champion he and Perry Martin bred for about $10,000, had set US racing alight with victories in the Kentucky Derby and Preakness Stakes.

But the final jewel in the Triple Crown escaped him on Saturday (Sunday AEST), as he finished equal fourth in a race won by a fresh-legged Tonalist whose connections had bypassed both the Derby and Preakness.

California Chrome suffered a hoof injury but it was not considered serious.

"This is his third very big race," Coburn said of California Chrome's five-week Triple Crown odyssey.

"These other horses, they always sat them out. I'm 61 years old and I'll never see in my lifetime another Triple Crown winner because of the way they do this.

"It's not fair to these horses that have been in the game since day one.

"To have somebody come up like this, this is a coward's way out," Coburn said. "This is a coward's way out."

Tonalist's owner Robert Evans would not rise to those remarks, saying Tonalist missed the Wood Memorial and the Kentucky Derby because of illness.

He credited US-based French trainer Christophe Clement with getting the horse ready for an unexpected May 10 victory in the Peter Pan Stakes at Belmont.

"Christophe Clement did a good job of getting him ready for the Peter Pan and he surprised me," Evans said.

"It wasn't a very nice day, there were thunderstorms, lots of rain and a muddy track and he just galloped and that's the clue he was a good horse because he was only three-quarters fit. So we had four weeks to get ready for this and Christophe had him just right."

Evans did not relish the role of spoiler in a sport that hasn't seen a Triple Crown winner since Affirmed in 1978.

"We loved California Chrome. We hoped he would win the Triple Crown," Evans said. "But we love our horse too."

Certainly Evans can sympathise with what Coburn and the rest of Chrome's connections are feeling.

Evans' father owned Pleasant Colony, who in 1981 finished third in the Belmont Stakes after winning the first two legs of the Triple Crown.

"I came in 1981 to the Belmont. We had high hopes for Pleasant Colony, I've been where Steven Coburn's been and it's not fun when you don't win," he said.

Evans said the change he would make to the Triple Crown would be to spread the races out more. Currently a fortnight separate the Kentucky Derby and Preakness in May, with the Belmont three weeks after the Preakness.

"It's better for the horses and it would be better to promote it, I think," he said.

"Racing has a problem in that it doesn't believe in marketing or selling itself and it should do more of that."