ELMONT, N.Y. — When Big Brown turned for home, something wasn't right.

Jockey Kent Desormeaux knew the big bay colt was finished. Trainer Rick Dutrow Jr., who guaranteed racing's first Triple Crown in 30 years, knew it, too.

Big Brown straggled home last yesterday, losing the Belmont Stakes to 38-1 long shot Da' Tara, who led wire-to-wire. Eased up in the homestretch, the 1-4 favorite was so far behind at the end that his margin of defeat wasn't even charted.

"He was empty. He didn't have anything left," Desormeaux said. "There's no popped tires. He's just out of gas."

Big Brown arrived at Belmont Park undefeated in five starts, winning all of them by a combined 39 lengths. His path to history seemed even more certain when unbeaten Casino Drive was scratched in the morning because of a bruised left hind hoof.

But he ran third most of the way until Desormeaux asked him for one of his explosive runs on the far turn of Belmont's 1 1/2 miles, the longest and toughest of the three classics.

"I had no horse," Desormeaux said, in stark contrast to Dutrow's unabashed pronouncements that a Triple Crown was "a foregone conclusion."

Instead of becoming the 12th Triple Crown winner and first in 30 years, Big Brown was the first horse going for a Triple to finish dead last, stunning 94,476 fans who braved the unseasonable 88-degree heat and oppressive humidity.

"He wasn't himself," winning trainer Nick Zito said. "Things happen for a reason."

Big Brown was running on a quarter crack in his left front hoof that wasn't patched until Friday, but Dutrow insisted even on the way to the starting gate that it was a "non-issue."

Nevertheless, it cost the colt three days of training between the Preakness and the Belmont. Desormeaux said Big Brown "was in no way, shape or form lame or sore. But there's something amiss, probably just tired."

Dutrow had been criticized for admitting he used a legal steroid on Big Brown, although the horse hadn't had a dose since April. Dutrow spoke only briefly after the race, and he wasn't asked whether discontinuing the drug had an affect on Big Brown's performance.

Big Brown's defeat extended the Triple Crown drought that began after Affirmed completed the elusive sweep in 1978.

"I feel for them. It doesn't always go the way you want," Steve Cauthen, who rode Affirmed, said by telephone from his Kentucky home. "I think someday a horse will come along and do it. One day it will happen. I really thought this was the horse."

Clearly, so did Dutrow.

The veteran trainer didn't speak when the race ended, walking quickly through the crowd with his eyes focused straight ahead as he tried to reach the track. Later, as Big Brown walked around the barn, Dutrow leaned on a wood railing, his head down, his blue dress shirt soaked with sweat, a look of disbelief on his face. Exercise rider Michelle Nevin stood silently next to him.

"Something has to not be right for him to be pulled up in a race, so I have to try to find out what it was," he said. "I'm sure it's not the horse's fault, so there's nothing to be down on him."

Big Brown, eager in the early going, ran up on Da' Tara's heels heading into the first turn — the first indication it wasn't going to be his coronation day.

Then Desormeaux tried to swing Big Brown wide to the outside and bumped Tale of Ekati in the turn.

Ridden by Alan Garcia, Da' Tara had the lead down the backstretch, with Tale of Ekati second and Big Brown third on the outside with a clear path. This was Big Brown's moment, and Desormeaux asked him to go.

"When I got outside going into the first turn, I said, 'This is it. The race is over. I got it,' " Desormeaux said.

Except Big Brown didn't respond.

Da' Tara opened up a clear lead turning for home, while Big Brown angled to the far outside under restraint. Big Brown still wanted to run, but Desormeaux knew it was over and focused on getting the colt home safely.

Big Brown was taken to a detention barn after the race for observation and will undergo various tests.

Dutrow said he didn't see a problem "and I'm looking for one."

"He looked fine," said Dr. Larry Bramlage, the on-call veterinarian. "All I saw was when Desormeaux started to slow him down. The first thing you expected is something is wrong. He was not lame when he stopped here in front of the stands."

Dutrow reflected on the Triple Crown that eluded yet another horse.

"We did really good with him winning the Kentucky Derby and the Preakness," he said. "This is a very disappointing race. Now, it looks like he's fine. It looks like he'll live a good life even if he never runs again."

Da' Tara, the longest shot on the board, won by 5 1/4 lengths over Denis of Cork and covered the distance in 2:29.65. There was a dead heat for third between Anak Nakal and Ready's Echo. Macho Again was fifth, followed by Tale of Ekati, Guadalcanal, Icabad Crane and Big Brown.

Da' Tara paid $79, $28 and $14.80. Denis of Cork returned $5.80 and $4.10. Anak Nakal paid $7.60 and Ready's Echo returned $6.20.

Zito spoiled a Triple Crown bid four years ago when he saddled Birdstone to an upset of Smarty Jones. He also trained Anak Nakal.

"If Big Brown was himself, he would've been tough to beat," Zito said, "but he wasn't himself. That's why they play the game."