Ever since a horse named Upset upset Man o' War at Saratoga almost a century ago, a horse that seems unbeatable can be beaten. Even the greatest of thoroughbreds can't seem to win them all. Even the best-loved of them can fail. And so it happened Saturday in the 136th Belmont Stakes. It happened to Smarty Jones.

Unexpectedly, excruciatingly, Smarty lost. He was out in front for a good part of the 1 1/2-mile marathon, the longest of the three classic races for 3-year-olds, but with the opportunity to become the first Triple Crown winner since Affirmed in 1978, he was run down and beaten by one length in the Belmont Park homestretch by a 36-1 shot, Birdstone, trained by New Yorker Nick Zito. Smarty, the Kentucky Derby and Preakness Stakes winner, was overtaken for the first time in his life.

Things like this happen all the time in horse racing, and they have happened often in the Belmont Stakes. Smarty Jones became the 10th horse since 1979 to fail in the Belmont with a chance to win the Triple. It happened to Spectacular Bid, Pleasant Colony, Alysheba, Sunday Silence, Silver Charm, Real Quiet, Charismatic, War Emblem and Funny Cide. It's happened six times in the past eight years.

This time, though, seemed as good as any for a horse finally to break through and take the elusive crown. Smarty went off a 1-5 favorite; only Secretariat before he won by 31 lengths in 1973 was more of a choice, at 1-9. The far-flung hopes of Smarty fans wherever sounded with the roar of a record Belmont crowd of 120,139 sensing history in the making as Smarty turned for home in front. But it was not to be. It was not to be, yet again.

"He's done some great things all year," trainer John Servis said of the little Philadelphia horse that in recent weeks had become "the people's horse," a nationwide celebrity. "I think if he were settled" -- relaxed as he was in previous races, instead of fighting jockey Stewart Elliott to run -- "we'd have had a Triple Crown winner. But I knew there was trouble on the backstretch. He wasn't settled. That was my concern the whole three weeks, trying to take the edge off. I wasn't able to do it. That's horse racing."

Winning jockey Edgar Prado apologized for his part in spoiling the Smarty party after guiding Birdstone to victory. "I had to do my job," Prado said in a television interview before he had even dismounted. "I'm very sorry it had to be me."

Zito was more obvious in his pleasure, winning his first Belmont, but still managed to keep his feelings low-key. Ironically, he was a New Yorker whom New Yorkers weren't rooting for, not on this day. He immediately congratulated Servis, saying he was "sorry." But Servis, in turn, told Zito he had done a fine job.

"I think this is my greatest win," Zito said. "Smarty Jones will still go down as one of the greats. I think he has a lot of racing left in him."

The dramatic outcome came less than two hours after the throng was informed by the public address announcer that former president Ronald Wilson Reagan had died. At 4:54 p.m., a hush came over the mammoth track as a moment of silence was observed. Horse players spoke of Reagan, whose lifetime encompassed all Triple Crown winners back to Sir Barton in 1919.

In the history of horse racing, it was believed that more money was bet on Smarty Jones than any horse ever. But as often happens, people go to a racetrack happy and leave in a different mood. If Zito, who also trained third-place finisher Royal Assault, was "happy and grateful," Smarty's fans were disappointed. From early morning on, they had streamed into the track. They wore Smarty Jones caps and T-shirts. Some carried Smarty hand fans strictly as souvenirs since they were of no value on a gray, breezy afternoon. Fans packed the paddock area to get a glimpse of Smarty being saddled. When he made his way onto the track, a great roar went up. And they bet with their hearts because $2 to win on Smarty would have netted only loose change. A Smarty winning ticket would have been worth more as a souvenir.

East side, west side, Smarty Jones had dominated conversations this week as New Yorkers co-opted Philadelphia's horse. Smarty had managed to bring together people in two cities as their rival teams in all major sports couldn't possibly. People bound for Belmont on Saturday but stuck in traffic reportedly were shouting "Go Smarty" from car to car, and even bounding out of their vehicles to give each other high-fives. Racegoers longed to see Smarty complete the Triple.

"Anytime a horse wins two legs of the Triple Crown, I come up from Florida," said Marcia Mathews, of Clearwater, who had staked out a spot near the paddock. "I've worn out all my friends coming here. It just never happens. The one I loved so much was Charismatic. I was crying hysterically. I was here last year for Funny Cide. Look around, people are happy. You have everybody here from babies in strollers to older people in wheelchairs. It's a uniting kind of thing."

United still as they filed out of the four-tiered plant, they were bemoaning Smarty's early move that took him to the front after a half-mile as well as Birdstone's late push. As Prado remarked, however, Birdstone was bred for the distance.

"I was very comfortable all the way around," he said, then turned his remarks to Smarty Jones. "I feel happy and sad at the same time because we are really looking for a champion. A mile and a half is a very tricky distance."

"More than anything," said Smarty's jockey Elliott, "I think it was the distance of the race, a mile and a half. It's a tough race."

It's why so many great horses have failed in the Belmont.

A 36-to-1 long shot, Birdstone, left, with Edgar Prado aboard, rallies to defeat Smarty Jones, with Stewart Elliott aboard, in Belmont Stakes.Fans at Smarty Jones's home track, Philadelphia Park, are left in disbelief.