A sloppy track could also be trouble for I'll Have Another; his lone finish outside the top two came on a soaked track at Saratoga in the Hopeful Stakes last September.
For all the things that might prevent him from winning, I'll Have Another has many believers.
"There's no question in my mind he can win it," said Motion, who raced Went the Day Well in the Derby (fourth) and Preakness (11th). "He's a quality horse, and he's shown it. But he's got to be right on the day. And he's got to have good luck. There are a few rested horses who seem to be on the cusp of big runs. He'll have to be at his best. But what we've seen so far is not a fluke."
One of I'll Have Another's most likely rivals, Dullahan, will ship into town Sunday after a fast one-mile work at Churchill Downs on Saturday.
"It's been a long time [since I had a horse work one mile]," trainer Dale Romans said. "He didn't seem tired afterwards, and he galloped out nicely."
O'Neill is counting on his horse's calm demeanor — and a skimpy racing schedule early this year — to push through the blockade that has stopped the 11 horses who came to New York seeking to end what is now a 34-year Triple Crown drought.
"He's got the mind," O'Neill said of his colt before leaving Baltimore. "You've seen the way he's handled the attention in Kentucky and here in Baltimore. He's got a great confidence about him, and he's got the stride of a horse that a mile and a half won't be a problem. He's got the pedigree; so much stamina on the female side.
"And he's lightly raced. After winning the Bob Lewis, it enabled us to give him plenty of time before his next start. He's still a fresh, happy, thriving horse that just seems to be getting better and better."
Rick Dutrow, the trainer of Big Brown, knows how difficult winning the Belmont can be. He guaranteed a win for his horse, who would be pulled up before the finish line.
"Of course this horse can do it," he said of I'll Have Another. "He's already proven he's the best. He's good. But that's got to hold. His health, his luck, his happiness. It has to hold."