EUGENE, Ore. — Tyson Gay got quite a fright in his first race yesterday. He set a record in his second.

Gay broke Maurice Greene's American mark in the 100 meters by running 9.77 seconds in his quarterfinal at the U.S. Olympic track and field trials.

"It tells me I'm in pretty good shape," Gay said. "We've got two more rounds left."

The U.S. contingent for the women's 100 was determined last night, and the biggest surprises might have been who did not make the team: Allyson Felix, whose specialty is the 200 but announced her intention to compete in four events in China, and Marshevet Hooker, who had the fastest time in each of the previous three rounds.

But Hooker was fourth and Felix was only fifth in the final. Instead, the three roster spots in that event went to Muna Lee in 10.85, and Torri Edwards and Lauryn Williams, two past world champions who both finished in 10.90.

"I'm definitely disappointed," Felix said. "The whole reason for running the 100 is to make the team. But I can't get too down. I still have the 200 to go."

Gay tied the fourth-fastest time in the history of the men's dash, despite clearly easing up a tad over his final few strides. Still, that was nothing compared to what he did in his opening heat earlier in the day, when Gay came awfully close to a monumental blunder.

After building a big lead, the reigning world champion eased up a lot with about 30 meters left — so much that the rest of the field began to catch him. Gay was forced to accelerate again and he lunged across the finish line in fourth place, good enough to advance.

"The first round I was scared. I almost started crying. I didn't know if I made it," Gay said after bettering the record Greene set in 1999. "This round I felt good."

As well he should. The performance had to be a big boost of confidence for Gay, who was a distant second — a spectator, really — in New York on May 31, when Jamaica's Usain Bolt broke the world record by clocking 9.72.

Gay's had to answer plenty of questions about how much of a challenge he'll present at the Beijing Olympics to Bolt and another Jamaican, previous world record-holder Asafa Powell.

Could Gay challenge Bolt's mark in today's semifinal or final?

"Anything's possible," said Wallace Spearmon, who sneaked into the semifinals by running 10.07. "Tyson's fast."

So is the track at Hayward Field, which already has produced two U.S. records in running events and is serving up the sort of dry, hot weather — the temperature hit 95 degrees yesterday — conducive to quick sprinting.

The runner-up in Gay's quarterfinal was Jeffery Demps of Okahumpka, Fla., who got out of the blocks a bit ahead of the favorite and wound up setting a national high school record at 10.01. In other words, this was a very fast race.

Olympic berths were finalized in two later events.

As expected, world champion Reese Hoffa, Christian Cantwell and two-time Olympic silver medalist Adam Nelson led the way in the men's shot put. Hoffa won with a top effort of 72 feet, 6 1/4 inches. Cantwell was second (71-2-3/4) and Nelson was third (68-6-1/2).

And in the heptathlon, Hyleas Fountain, Jacquelyn Johnson and Diana Pickler qualified to go to Beijing.