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Triple Crown hopeful Big Brown is ridden by exercise rider Michelle Nevin on Friday at Belmont Park.

NEW YORK — The Triple Crown trail is littered with colts whose feet failed them along the way. Less than 24 hours before the biggest horse race in three decades, favorite Big Brown and his Japanese challenger, Casino Drive, took steps in opposite directions.

The cracked hoof that stood between trainer Rick Dutrow Jr.'s big bay colt and the sport's first Triple Crown since 1978 was covered with an acrylic patch Friday, ending a weeklong drama.

No sooner had the glue dried on Big Brown when Casino Drive turned up with a suspect foot that could knock the early second choice out of the Belmont Stakes.

If he's scratched from Saturday's punishing 1 1/2-mile race, it would eliminate Big Brown's chief rival, the only other undefeated colt in the field and send Dutrow's brimming confidence over the top.

"I don't think Casino Drive has any chance at all," he said. "I think the horse has got his issues."

Of course, that would leave eight other horses to take a shot at Big Brown, the early favorite. Dutrow seemed even less worried about them, saying, "They're going to have to run the race of their life to win."

At 2-0, Japan-based Casino Drive is coming off a 5 3/4-length victory in the Peter Pan Stakes nearly a month ago on the same Belmont track.

"Right now, we are in. We expect him to run," said Nobutaka Tada, racing manager for owner Hidetoshi Yamamoto and trainer Kazuo Fujisawa.

Big Brown is seeking to join Seattle Slew (9-0 in 1977) as the only undefeated Triple Crown winners. He's won all five of his races by a combined 39 lengths.

"There's excitement in the air," said Dutrow, who memorably declared that Big Brown winning the Belmont is a "foregone conclusion."

It seemed that way for Spectacular Bid, another horse with the same aura of invincibility, whose attempt at sweeping the Kentucky Derby, Preakness and Belmont was derailed in 1979 when he stepped on a safety pin the morning of the Belmont.

The pin was still lodged in his hoof when jockey Ron Franklin rode him to a third-place finish.

Big Brown's hoof issue was resolved out of public view, with hoof specialist Ian McKinlay applying an acrylic and fiberglass patch to the colt's front left hoof.

"There were no problems," he said afterward. "Things couldn't be better. It's time for history."

McKinlay removed the stainless steel sutures holding the crack together, cleaned the area, redrilled holes and put in new sutures. Then he covered it all up with an acrylic adhesive — the same kind used for the $550 glue-on shoes Big Brown wears on his front feet — that set in five minutes. The entire process took about 30 minutes.

"That'll be actually stronger than his hoof will," McKinlay said. "That'll probably be the last time I'll work on that hoof unless something else crops up. It could be two months down the line that something else could happen."

The patch will be left on indefinitely, growing out as Big Brown's nail grows.

Taking a page from Dutrow's brag book, McKinlay guaranteed his work.

"If that patch comes off in this race, I might as well quit what I'm doing," he said. "There is no shot at that."

If McKinlay's wrong, he may need to find another job.

He did leave himself an out, explaining that if an infection is lurking in Big Brown's hoof, it could be aggravated while using heat to apply the patch. An infection wouldn't surface for another three or four days, though.

"I don't expect anything to go wrong with this certainly before tomorrow and not even down the line," he said. "He looks fabulous."

Casino Drive, meantime, skipped going to the track. His left hind foot didn't look good to his handlers when they checked him Friday morning.

"We are not 100 percent happy with the movement of his hind leg," Tada said. "There is a slight possibility of a bruise."

Edgar Prado, set to ride Casino Drive, was surprised at the development.

"That's not good news," he said. "You want him to come to a race 100 percent. Definitely it's a setback. Hopefully, they'll be able to fix him, and he'll be in the starting gate tomorrow."

Casino Drive galloped on the track Thursday but didn't seem to like the muddy surface.

Tada said a veterinarian saw the horse, whose hoof was alternately being soaked in ice and epsom salts and then having heat applied. "He probably stepped on something or kicked something," Tada said. "He looks fine, he has a good appetite. He's not lame."

Tada said Casino Drive may have a stone bruise, which can be caused by walking on hard, rocky ground. The colt has gone for long walks all over Belmont Park's horse paths this week, a training technique favored by the Japanese. American trainers typically gallop, jog and breeze their horses on the track in the days leading to a race.

"All we missed was jogging him on the track. If he stays like now, there is nothing to stop him," Tada said. "It's just a minor issue, we hope."

Casino Drive was pointed toward the Belmont because of his breeding. His dam produced the last two winners: filly Rags to Riches last year and Jazil in 2006.

"We are planning on running," Tada said, "but we have to be sure he is well."