BEIJING — China didn't just walk onto the world stage. It soared over it.

At last playing its long-sought role as Olympic host, China opened the Summer Games in spectacular fashion today with an extravaganza of fireworks and pageantry dramatizing its ascendance as a global power.

Disasters, environmental problems and human-rights disputes preceded the games, and questions abound about how they will unfold. But for an evening, at least for the 91,000 people packed into the new National Stadium, it was an interlude of fervor and magic — capped by the spellbinding sight of a skywalking, torchbearing gymnast floating around the stadium's top rim before sending a torrent of fire upward to light the Olympic flame.

Scores of world leaders were on hand, and the potential TV audience was 4 billion worldwide for what was certainly the costliest and probably the largest opening ceremony in Olympic history.

The centerpiece was the parade of athletes, climaxing with the entry of the 639-strong Chinese team. Its flag-bearer was basketball idol Yao Ming, accompanied by 9-year-old schoolboy Lin Hao, a survivor of May's devastating earthquake in Sichuan province.

A chanting, flag-waving crowd gave a thunderous welcome, and erupted again a few moments later when President Hu Jintao declared the games open.

President Bush and Russian Prime Minister Vladimir Putin were among the glittering roster of notables who endured heat and humidity to watch China make this bold declaration that it had arrived. Bush, rebuked by China after he raised human-rights concerns this week, is the first U.S. president to attend an Olympics on foreign soil.

Already an economic powerhouse, China is given a good chance of overtaking the U.S. atop the gold-medal standings with its legions of athletes trained intensely since childhood. One dramatic showdown will be in women's gymnastics, where the U.S. and Chinese teams are co-favorites; in the pool, Chinese divers and U.S. swimmers are expected to dominate.

The run-up to the games had powerful story lines — China investing $40 billion to build Olympic infrastructure, reeling from the Sichuan earthquake, struggling right through Friday to diminish the stubborn smog that enveloped the stadium, known as the Bird's Nest. China's detentions of political activists, its crackdown on uprisings in Tibet and its economic ties to Sudan — home of the war-torn Darfur region — fueled persistent criticisms from human rights groups and calls for an Olympic boycott.

Second-guessed for awarding the games to Beijing seven years ago, the International Olympic Committee stood firmly by its decision. It was time, the committee said, to bring the games to the homeland of 1.3 billion people, a fifth of humanity.

"For a long time, China has dreamed of opening its doors and inviting the world's athletes to Beijing for the Olympic Games," IOC president Jacques Rogge said in his speech. "Tonight, that dream comes true."

Rogge mentioned the earthquake, saying the world was moved "by the great courage and solidarity of the Chinese people." And he exhorted the assembled athletes, as role models for the world's youth, to "reject doping and cheating."

The story presented in today's pageantry sought to distill 5,000 years of Chinese history — featuring everything from the Great Wall to opera puppets to astronauts, and highlighting achievements in art, music and science. Roughly 15,000 people were in the cast and crew, all under the direction of Zhang Yimou, whose early films often ran afoul of government censors for their blunt portrayals of China's problems.

He produced some majestic and ethereal imagery. At the start, 2,008 drummers beat out a pulsating rhythm with their hands. Later, a huge, translucent globe emerged from the stadium floor, and acrobats floated magically around it to the accompaniment of the games' theme song, "One World, One Dream."

It ended in spectacular fashion, when China's first Olympic superstar, 1984 gymnastics triple gold medalist Li Ning, was hoisted by wires to the top of the stadium, circled the entire circumference as though he was spacewalking, then used his torch to send a torrent of flame spiraling upward to light the Olympic flame in a huge cauldron overlooking Beijing.

Li, now 44, whose six medals total at Los Angeles in 1984 signaled China's intention to be a sports powerhouse, admitted to being nervous about "the best memory of my life."

"This is a glorious but also huge task for anyone," he said. "I should never let the dream of all the Chinese people down. That was why I was nervous."

Li had trained for his part for a month. "The biggest problem is the wind," he said. "Every time I must balance myself in the air and hold the torch as close to the cauldron gas outlet. But every time the wind blew in different directions."

There were no such problems today, and when it was over, Li basked in his success. "That moment," he proclaimed, "means China is standing side by side with the rest of the world."

The show's script steered clear of modern politics — there were no references to Chairman Mao and the class struggle, nor to the more recent conflicts and controversies.

A record 204 delegations paraded their athletes through the stadium — superstars such as tennis great Roger Federer and basketball's Kobe Bryant, as well as plucky underdogs from Iraq, Afghanistan and other embattled lands. The nations marched not in the traditional alphabetical order but in a sequence based on the number of strokes it takes to write their names in Chinese. The exceptions were Greece, birthplace of the Olympics, which was given its traditional place at the start, and the Chinese team, which lined up last.

The U.S. team — second-largest after China's with nearly 600 members — was welcomed loudly, with many in the crowd recognizing Bryant and other basketball stars who brought up the rear. Bush rose from his VIP seat to wave at the athletes, nattily dressed in white trousers, blue blazers, red-white-and-blue-striped ties and white caps.

"It was a breathtaking experience walking into the stadium," said Oganna Nnamani, a volleyball player from Bloomington, Ill. "I am thankful to be part of this moment."

"This is the biggest stage," said LeBron James, who hopes to lead the U.S. basketball team to a gold medal.

Among the flag-bearers were basketball stars Dirk Nowitzki of Germany and Manu Ginobili of Argentina, and South African swimmer Nathalie Du Toit, who lost her lower left leg in an accident and made history by qualifying for both the able-bodied games and the Paralympics.

The American flag-bearer was 1,500-meter runner Lopez Lomong, one of the Lost Boys of Sudan, who spent a decade of his youth in a refugee camp in Kenya. He's a member of the Team Darfur coalition, representing athletes opposed to China's support for Sudan. Today he avoided any criticism and said the Chinese "have been great putting all these things together."

Abroad, human rights activists were less generous.

"The Chinese government and the International Olympic Committee have wasted a historic opportunity to use the Beijing Games to make real progress on human rights in China," said Sophie Richardson of Human Rights Watch.

Few Olympics-related disturbances were reported in China. But in Katmandu, Nepal, hundreds of Tibetan exiles demonstrated outside the Chinese embassy, demanding an end to what they say is Beijing's brutal rule. In Turkey, an anti-China protester set himself on fire.

By all indications, the Chinese have overwhelmingly embraced the games, buying up tickets at a record pace, volunteering by the thousands for Olympic duties, nursing expectations of triumphs by their home team.

To their eyes, the omens were good. The ceremony began at 8 p.m. on the eighth day of the eighth month of 2008 — auspicious in a country where eight is the luckiest number.