As the stadium announcer introduced the world's fastest man Wednesday night, Usain Bolt rose up the entire length of his 6-foot-5 frame and pretended to wipe sweat from his head. Then he pointed at the 91,000 adoring fans at the Bird's Nest who had come to witness sports history.

After the pre-race show, the Jamaican sprinter lowered into the starting block on this late summer night. Then the report of the gun echoed in the still air. A cheer rose.

And then it was over. Bolt's great stride made the world's best sprinters look like children trying to keep up with an older brother. He won the 200 meters in 19.30 seconds, breaking Michael Johnson's 12-year-old world record by two-hundredths of a second.

"I blew my mind and I blew the world's mind,'' Bolt said.

The performance was so devastating to the rest of the field that it seemed almost incomprehensible. And it happened on a bizarre night in which two other medalists were disqualified for stepping on the line, giving the United States' Shawn Crawford the silver and Walter Dix the bronze.

Bolt, who turned 22 today, won by the biggest margin since the 200 meters became an Olympic event 108 years ago. He annihilated the field by 0.66 of a second, an unheard-of margin in a race measured by hundredths of a second. Crawford, the defending Olympic champion, crossed the line in 19.96 seconds, leaning to edge out Dix (19.98).

Bolt's victory marked the first time a man has won both the 100 and 200 at the Olympics since Carl Lewis did it in 1984. The Jamaican also is the first to break the world record in both sprints at a single Olympics. His performance is likely to join that of Lewis and Jesse Owens among the pantheon of greats.

Unlike on Saturday, when he downshifted well before the finish of the 100 meters, Bolt charged down the stretch. The timing clock froze at 19.30. Bolt stretched his arms wide and crumbled to the ground. He got on his knees and buried his head in the track, and then, with reggae music blaring, he danced.

The Jamaicans' golden touch continued a half-hour later when Melaine Walker defeated Sheena Tosta of the United States to win the 400 hurdles in an Olympic-record time of 52.64 seconds. Caribbean sprinters have dominated the Americans, with more medals expected tonight in the women's 200 final.

And in the process, Bolt has become the Michael Phelps of track, with his mind-boggling performances.

"This is a phenomenon,'' said Herb Elliott, the team's chief physician, who first saw Bolt as a 13-year-old. "We're saying a Usain Bolt comes once every century.''

Even Bolt is impressed. During a news conference he paused from a question to watch a replay of his race.

"Cool,'' he said. "That guy's fast.''

Some wonder if he is too fast. Jamaica's drug-testing standards have come under scrutiny during the Olympics because of the stunning success. But Elliott was defiant in defense of his country's policies. He said he tests the athletes regularly, which proves they are clean.

But experts agree that legitimate independent programs do not employ a person involved with the team — such as Elliott — to conduct their testing, so the doctor's denials are not likely to end the doubts.

Despite the suspicions, Bolt and the other winners here have not tested positive. Bolt's rivals can't explain the success. They just marvel at it.

"He's bad,'' Crawford said. "He's revolutionized the game.''

Before this year, few knew much about Bolt, who was a junior world champion and has been a rising star since the Athens Games. But after he set a world record of 9.69 seconds in the 100 on Saturday, his competitors hoped the demanding rounds of racing here would catch him — if they couldn't.

"I never thought he was going to be right there with me, but he was,'' Dix said of seeing Bolt on the turn in the 200. "Stuff happens.''

All kinds of strange stuff took place after the race. Wallace Spearmon finished third, and he took a victory lap with the American flag draped around him. But while posing with the other medalists he was told of his disqualification for a lane violation. "Who me?'' he mouthed.

While reviewing film of the race, U.S. officials discovered second-place finisher Churandy Martina of the Netherlands Antilles also had crossed his lane illegally. They protested, and he, too, was disqualified.

Omayra Leeflang, minister of sport for Netherlands Antilles, criticized the protest. "It's a pity for a big country like the U.S. to make such a small statement,'' he said.