EUGENE, Ore. -- Tyson Gay accelerated through the first curve. Then, he started flying.

Not in the figurative sense, but in an all-too-real way -- a shocking sprawl to the ground in the semifinals that cost America's best sprinter an Olympic spot in the 200 meters and made him look like less than a sure thing, health-wise at least, with the Beijing Games five weeks away.

Gay suffered what his manager called a severe cramp in his left hamstring at the U.S. Olympic Track and Field Trials yesterday and had to be carted off the track. He was at his hotel later, being treated with ice.

"It was just one of those things," Gay said in a statement released through USA Track and Field.

Gay already has qualified for the Olympics in the 100 meters, but his chances at doubling are gone. Now, the nervous wait begins to see if it was, indeed, just a cramp, and how that affects his training the next month.

"There is no apparent damage otherwise, except for some road rash from the fall," said Gay's manager, Mark Wetmore. "He said he felt a little tightness before the race."

Wetmore said Gay was getting an MRI as a precaution. Results were not immediately available.

"When he wakes up [today], he'll know," said former decathlete Dan O'Brien, who famously missed the Olympics 16 years ago. "He'll be able to stretch it out, he'll be able to move it. If he can't sit on the toilet [today], he's got problems."

Had this been gymnastics, or a number of other sports, an injury at trials wouldn't have ended Gay's chance to make the Olympics in that specific event. But USA Track and Field plays it straight -- top three finishers at trials make the Olympics, no exceptions.

It's a black-and-white policy that most athletes accept, though it could end up costing the American team as much as Gay in Beijing. Gay is the defending world champion in the 100 and 200 meters.

"I don't know any other way to do it, but it's tough," said Wallace Spearmon, now the favorite in today's finals.

It was, in fact, a stunning setback for Gay, 25, who last week set the American record in the 100 at 9.77 seconds. In the final, he ran it in 9.68, the fastest time ever recorded, but not a world record because the tailwind was too strong.

Damein White, running in the lane next to Gay, said he saw Gay pull up and saw something fly his way. It was the white sticker with Gay's number on it.

"I tried to keep going off the curve," White said. "It kind of threw me off. He just pulled something. He'll be right back. Next year, we've got worlds. You'll see him there."

More urgently, however, are the Olympics. Qualifying for the 100-meter dash starts Aug. 15, and Gay was one of the favorites, along with world-record holder Usain Bolt and Asafa Powell, both of Jamaica.

The injury will open up another spot in the 200, where Gay, Spearmon, Xavier Carter, defending Olympic champion Shawn Crawford and Walter Dix were considered among the top runners going for only three spots.

There were no more surprises in the 200 semifinals later yesterday, when all the top contenders advanced. Same in the women's heats, where Allyson Felix, 100 champion Muna Lee, Lauryn Williams and Torri Edwards all made it to today's finals without much drama.

Gay's injury, however, made the day a little difficult for everyone involved.

"It's such an awful thing when bad things happen to good people," Williams said.

If his injury truly was only a cramp, he could be back on the track soon.

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