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Far ahead halfway through his 100-meter Olympic quarterfinal, Usain Bolt casually swiveled his head to his right, to his left, then back to his right.

Never hurts to check. No one was nearby — hardly surprising, given how quickly the 6-foot-5 Bolt's long strides carried his golden spikes. So the world record-holder slowed to what for him amounts to a jog.

He still crossed in 9.92 seconds, a time that makes it the fastest dash ever run in China, a time that would have earned a medal at all but two previous Summer Games and a time that fails to reflect how effortless Bolt's performance was.

The Jamaican licked his lips, checked the scoreboard and pumped a fist, his untucked yellow sleeveless shirt rippling. The message, to himself and to rivals Asafa Powell and Tyson Gay, was unmistakable:

Bring on Saturday's 100 semifinals and final.

• Click here for Friday's Olympics photos.

"I just ran the first 50 meters, then I looked around to make sure I was safe, and I shut it off," Bolt said Friday night. "I'm ready for my best."

Goodness. Remember, this is a guy who said as recently as last week that he wasn't sure whether he would race the 100 — an event he only began pursuing seriously this year — in addition to his specialty, the 200, at these Olympics.

"He's a phenomenal athlete," said Darvis Patton of the United States, who also advanced to the semifinals.

Bolt, his Jamaican teammate Powell and U.S. record-holder Gay — the reigning world champion who hadn't raced in 1 1/2 months because of a left leg injury — all advanced without a hitch through two 100 heats Friday, when the 10-day track and field competition opened.

The first medal final, the men's shot put, was most foul for a U.S. contingent that was hoping for a sweep. Instead, the Americans settled for a silver from Christian Cantwell behind champion Tomasz Majewski of Poland, whose winning throw of 70 feet, 7 inches (21.51 meters) was more than three feet shy of the personal bests of all three Americans.

"Inexcusable," said two-time Olympic silver medalist Adam Nelson, who couldn't overcome aching ribs and fouled on all three of his attempts.

The third U.S. finalist in the event, 2007 world champion Reese Hoffa, fouled on his last two heaves and wound up in seventh place.

"We expected more from ourselves," Nelson said. "We're all disappointed. We all wanted a sweep."

Cantwell seemed less than thrilled, holding up two fingers to signify second place and sticking his tongue out.

"I'll take it, I guess — silver's silver," he said.

Shalane Flanagan, meanwhile, was thrilled with the bronze medal she earned for the United States in the women's 10,000 meters.

As she crossed the finish, behind winner Tirunesh Dibaba of Ethiopia and runner-up Elvan Abeylegesse of Turkey, Flanagan put her hands on her head, then raised three fingers and looked for some confirmation that she had, indeed, managed to win a medal.

"Oh, my God. Am I three?" she asked. "Am I third?"

She sure was, collecting the first Olympic medal for the U.S. in the women's 10,000 since 1992. It was a run Flanagan, the U.S. record-holder, wasn't sure she had in her earlier in the week when she was hit with what she thought was food poisoning.

"It was not pretty for about 48 hours," she said.

Dibaba, twice a world champion, finished in 29 minutes, 54.66 seconds, an Olympic record. Abeylegesse also needed less than a half-hour, something only one other woman ever had done before Friday.

It was precisely the sort of performance in a distance event that some worried might not be possible in the heat, humidity and, of most concern, pollution of August in Beijing.

Thanks, perhaps, to an overnight rainstorm, competition began Friday morning under a crystal blue sky marked by only the occasional soft puff of cloud — quite a contrast from the dark haze hanging over the city for much of the Olympics' first week.

"Smog?" said Nataliia Dobrysnka of Ukraine, second behind Hyleas Fountain of the U.S. after Day 1 in the heptathlon. "No problem."

Friday also included the Olympic debut of the women's 3,000-meter steeplechase — which featured a slip-and-spill pileup in a water trough — and qualifying for the men's 1,500. All three U.S. entrants are still in the medal chase there: Bernard Lagat, who won a silver and bronze for Kenya at past Olympics; Lopez Lomong, a "Lost Boy" refugee from Sudan who carried the American flag during the opening ceremony a week ago; and Leo Manzano, who was born in Mexico.

The 91,000 seats at National Stadium — commonly referred to as the Bird's Nest because of the latticework on the outside that looks like crisscrossed twigs — were mostly full during the evening session.

The proceedings had the feel of an American sports venue: Male and female cheerleaders shook pink and silver pompons; songs by U.S. rock band Green Day and singer Sheryl Crow blared on loudspeakers; fans did the wave.

The loudest ovations were reserved for Chinese competitors, but the applause and yells were plenty loud for the 100 heats.

"It felt pretty relaxed," Gay said after clocking 10.09 seconds in his quarterfinal. "I just wanted to make it through."

That he did, setting up a head-to-head semifinal showdown against Powell. Gay showed no signs of the hamstring strain that sent him sprawling to the track during qualifying for the 200 at the U.S. Olympic trials in July.

As if to prove that troublesome muscle is really no trouble at all these days, Gay hopped over a barrier to avoid a swarm of reporters following his second heat, then relented for a brief interview.

The only person Powell spoke to after running his quarterfinal was Bolt. They walked past reporters side-by-side, two countrymen and two competitors chatting about who knows what as a barefoot Bolt toted those gold shoes of his.

He had to wait to resume his pursuit of a medal to match.