BEIJING — In any other city, at any other stadium, under any other circumstances, Liu Xiang might not have shown up at all.

His right hamstring’s been bothering him for months. A tendon in his right foot flared up a couple of days ago.

This, however, was far from any old setting. This was the Bird’s Nest, the 91,000-seat centerpiece of the Olympics. The Beijing Olympics. And this was a moment, shortly before lunchtime Monday, that Liu’s country of 1.3 billion had anticipated for years: China’s only track and field superstar — one of China’s most recognizable faces, period — competing to defend his 110-meter hurdles title at home.

And it ended after all of two full strides.

Liu pushed out of his crouch, planted his left foot, then his right, then landed again on his left and began hopping on the good leg, dragging his bad one, as a second gun sounded to signal a false start by another runner. No one is disqualified by an initial false start, but Liu immediately tore the piece of paper with his number off each leg and headed for a tunnel, stepping gingerly all the way.

Just like that, his Olympics were over, later signified in the black-and-white parlance of the results sheet as “DNF” — “Did Not Finish.”

He left the stadium without speaking to reporters; China’s track and field coach, Feng Shuyong, relayed that his hurdler was “very depressed.”

“He couldn’t imagine the pain he was suffering,” Feng said. “Let me repeat: Liu Xiang will not withdraw unless the pain is unbearable.”

Feng spoke at a news conference where tears flowed freely. Liu’s personal coach, seated beside Feng, broke down soon after beginning to speak. Members of the Chinese media wept openly.

Liu’s pursuit of the gold was supposed to be one of the main story lines of these Summer Games, from Monday’s first round of qualifying through Tuesday’s second round, Wednesday’s semifinals and Thursday’s final.

“Everyone expected Liu to do well, as well as he did four years ago,” Feng said. “That is the wish of all Chinese people.”

For Liu has come to represent his nation’s desire for international recognition and respect.

So Liu tried. Oh, did he try. He tried to stretch and slap and massage leg muscles and will them to work. He tried to hide his anguish by pulling his red warmup shirt over his head.

Most of all, he tried to live up to the expectations of a nation and of sponsors that include Coca-Cola and Visa. He has all the trappings of modern celebrity, rivaled among Chinese athletes only by Houston Rockets center Yao Ming: Liu croons in a music video, appears in TV commercials, and looks down on China’s streets from billboards bearing his mug — in a leather jacket for Cadillac, in running gear for Nike.

This is a man whose legs were insured for about $13 million.

Fans and Chinese officials responded to the marketing and his results by treating Liu as someone who proved an Asian athlete could beat the rest of the world on the track.

These were expectations thrust upon him since that day four years ago at the Athens Games when he became the first man from China to win an Olympic gold medal in track and field. He followed that with a gold at the 2007 world championships.

Even before the 25-year-old Liu emerged onto the sun-soaked track today, his body language signaled duress. Waiting with other hurdlers for their heat, he paced about, at one point vigorously kicking a padded wall with his right shoe. He kept flexing his right leg and ankle.

When he cleared two hurdles in warmups, then stopped abruptly, others noticed.

“We could see he wasn’t quite as strong as you expect him to be,” a former world record-holder, Colin Jackson, said. “But we didn’t know it was as bad as it turned out to be.”

Once on the track, Liu favored his right leg — the leg he pushes off to clear hurdles. He rubbed his knee. He peeled off his warmup shirt when others were lining up behind the blocks and seemed to wait forever before pulling his racing singlet over his head.

Grimacing and gritting his teeth all the while.

After the false start, while other entrants in his heat prepared for the race to begin again, Liu trudged away slowly, painfully, alone. Fans gasped. Was he quitting? He continued his departure, along a concrete path into the shadows beneath the stands. Plopping on the ground, leaning against a red wall, he sat by himself, a sullen expression in place of that famous, square-jawed smile. Moments later, he covered his face with a red shirt and was given a clear plastic bag of ice for his ankle.

Eventually, he rose, pulled on red warmup pants and limped away.

By then, tens of thousands of spectators were gone.

Hard to imagine such a large sporting venue emptying as quickly as this one did.

“I feel very sad for Liu Xiang,” one of the departing fans, 67-year-old retiree Liu Guixiang, said. “After Liu Xiang’s injury, I won’t bother coming back to the Bird’s Nest for more.”

Liu’s personal coach, Sun Haiping, said through a translator that Liu was bothered by a right foot injury that has lingered for six or seven years — and that the pain intensified Saturday.

“I also feel very bad about today’s result,” said Sun, his shoulders shaking.

Liu’s hamstring problem forced him to pull out of a meet in New York on May 31 — the same night Usain Bolt first broke the world record in the 100 meters.

A week later, Liu lined up for the Prefontaine Classic at Eugene, Ore., but was disqualified for a false start. He hasn’t raced since and only rarely appeared publicly, training in seclusion and even skipping the Olympics’ opening ceremony.

“I think the Chinese people will understand the situation,” Feng said of Liu’s withdrawal, “and will encourage him to come back to the track.”

The 110-meter hurdles final was expected to be one of the highlights of these Olympics: China’s Liu vs. Cuba’s Dayron Robles, the man who broke Liu’s world record in June — with a packed house ready to cheer on their man.

“I think they will be disappointed. But they will understand,” the executive vice president of the Beijing Olympics’ organizing committee, Wang Wei, said. “When somebody has an accident, you can’t help it.”

Now Robles, who won his heat today, becomes the clear favorite — helped also by the “DNF” for two-time Olympic silver medalist Terrence Trammell of America. Trammell strained his left hamstring and cleared only the first hurdle of his heat before pushing the second hurdle with his hand, kneeling briefly and then refusing a stretcher as he limped off the track.

Within a few minutes of Liu’s exit, his personal Web site carried the news. Within a few hours, nearly 1,000 entries from readers expressed warm wishes and encouragement, and in some cases, disappointment.

Robles’ reaction? Not exactly brimming with sympathy.

“To tell you the truth, I don’t care,” said the Cuban, who also promised a new world record. “I just came here to compete and take the gold. I don’t care who’s on the track.”