Sometimes the past and the future share a stage. As yesterday’s gold medalist headed home, tomorrow’s Olympian began preparations for London, both doing so at times in spectacular fashion at the U.S. Olympic track and field trials.

In the decathlon, Ashton Eaton set a world record Saturday evening. He tallied 9,039 points, won seven of 10 events and stirred a partisan crowd that cheered the 24-year-old Bend, Ore., native in steady rain and cool temperatures.

So impressive was Eaton’s performance that Dan O’Brien, the 1996 Olympic gold medal-winning decathlete, called it the “finest day in decathlon history.”

“The great thing about this is — not to pump my own tires or anything — I feel like I have not maximized yet,” Eaton said. “I feel like I can still run faster, jump higher.”

Eaton’s final numbers certainly raised expectations for the London Games. But the bigger surprise in the opening days of these trials was found near the bottom of the decathlon standings.

Bryan Clay still is considered one of the world’s best, but he won’t be competing in a third Olympics after his 12th-place finish Saturday, which included a disastrous showing in the 110-meter hurdles.

Clay, the 2008 Olympic gold medalist, was in third place through five events but began Saturday morning by hitting hurdles Nos. 8, 9 and 10. He was initially disqualified, a decision that was overturned later, but three fouls in the discus formally ended any hopes for London.

“The whole time throwing discus, my mind just wasn’t there,” Clay said.

Several other athletes earned their tickets to the Summer Games on Saturday evening, but at least two left Hayward Field with their Olympic hopes still very much up in the air.

In the women’s 100 meters, Carmelita Jeter won with an impressive 10.92-second finish, followed by Tianna Madison (10.96) and then Jeneba Tarmoh and Allyson Felix, who finished in a dead-heat tie with a time of 11.068.

Tarmoh was initially named the third-place finisher, one-thousandth of a second ahead of Felix, and was introduced at a post-race news conference as London-bound.

She expressed excitement to reporters, while Felix struggled to swallow the result. “It’s the worst,” Felix had said. “Just disappointed.”

But an hour later, officials with U.S.A. Track and Field said a photo review showed the two sprinters appeared to cross the line at the same time. Officials said there is no formal procedure in place to break the tie, and it wasn’t immediately clear Saturday night which of the two would go to London. Only three Americans can race in the 100 meters at the Summer Games.

It was a murky conclusion to a gray, rainy Eugene day. Emotions washed over winners and losers alike.

While the track trials crowns Olympians and validates years of hard work for a select few, many others leave historic Hayward Field with only disappointment.

Dawn Harper will aim for a second Olympic gold medal in the 100-meter hurdles after topping the field with a time of 12.73 seconds. She will be joined by second-place finisher Kellie Wells (12.77) and crowd favorite Lolo Jones (12.86), who made the team by just four-hundredths of a second.

Meanwhile, sprinter Lauryn Williams and hurdler Joanna Hayes, who won silver and gold in their respective events at the 2004 Games, both failed to qualify for London.

Hayes, 35, gave birth to a baby girl less than two years ago and her bid to return to the Olympic stage ended in a semifinal heat. She wept afterward but said she was not sad.

“All I could think about was doing something to make [my daughter] proud,” she said through tears.

Tears take on different meanings when so much is at stake. Adam Nelson, a thick tree stump of an Olympian who won silver in the shot put at the 2000 and ’04 Games, momentarily caught his breath and tried to explain.

“I’ve been fortunate to have a great team behind me, my wife . . .” he said, before falling into Laci Nelson’s arms and rousing a new round of tears for both. “You guys know I’m an emotional guy, so it’s all right, right?”

Nelson’s bid for a third Olympics was cut short as he finished 15th in the preliminary round and wasn’t one of the 12 who advanced to Sunday’s finals.

Nelson, 36, wasn’t ready to announce his retirement but conceded, “I definitely am getting older and Father Time does take its toll.”

Other past Olympians were still fighting to compete another day. Jeremy Wariner, who won four Olympic medals in the past two Summer Games, posted the seventh-best time in Saturday’s semifinal to barely earn one of eight spots in Sunday’s 400-meter final. His finishing time of 45.27 seconds was well off the pace set by the day’s fastest runner, LaShawn Merritt, who ran the 400 in 44.78.

In the men’s 100 meters, several of the favorites advanced to Sunday’s semifinals with impressive times in the preliminary rounds. Justin Gatlin, the 2004 Olympic gold medalist, finished in 9.90 seconds, Tyson Gay had the day’s second-best time (10 seconds), followed by Ryan Bailey and Walter Dix (both 10.03).

Decathete Trey Hardee (8,383 points) is also headed to London, but over the course of 10 events in two days, Eaton showed he’s currently in his own class.

“I don’t know if anybody’s ever matured in the event as quickly as he has,” Clay said. “It’s mind-boggling to see his performance and to see how well he’s done in such a short amount of time.”

Future medalists are culled from a large field, but the trials also provide a stage for many stars to take a final bow. On Sunday, seven more finals are on tap, seven more chances to say hello to new Olympians and good-bye to old ones.

“It’s okay, this is a great occasion,” Nelson said before leaving. “The Olympic trials is where it starts for a lot of people. I saw a lot of new beginnings out there today.”