DES MOINES, Iowa (AP) — Tyson Gay was barely out of breath after breezing through his 100-meter heat. Moments later, Justin Gatlin was hardly even huffing after he finished.

Gay and Gatlin scarcely worked up a sweat as they easily cruised through the first round of the 100 on Thursday at the U.S. track championships. Their times were not blistering, but that wasn't the point on this windy day, only advancing in as little effort as possible.

By moving on, they're moving toward a showdown in Friday's final.

"It felt good," said Gay, who trimmed his hair to be more aerodynamic. "Just get the nerves out."

This was a game within a game between the two — show just enough, but not too much.

Gay powered down his lane to win his heat in 10.28 seconds. Gatlin easily cruised across the line in 10.37, taking second in his heat. He estimated he ran at maybe 70 percent, conserving his energy for when he really needs it, possibly to hold off Gay.

"Tyson is something of an enigma," Gatlin said. "When he's healthy, he's one of the most dangerous sprinters you can compete against."

And Gay's healthy, maybe as healthy as he's ever been. Asked about his hip, the one that's given him problems for quite some time, Gay simply said, "Feeling good."

Gay has the world's top time this season. But Gatlin has something perhaps even more impressive — a recent win over Usain Bolt, which very few sprinters have done since the Jamaican's rise to power.

While Gay and Gatlin were the center of attention early on at nationals, Dentarius Locke of Florida State stole some of the spotlight as he turned in the top time of 10.19, just ahead of Jeff Demps.

"I just went out there and ran my race," Locke nonchalantly said. "I know tomorrow will be a different day. Hopefully everything will fall into place."

Things certainly fell into place for Galen Rupp, who closed out the first night of competition by winning his fifth straight 10,000-meter national title.

"Just keep it rolling as long as I can. It's fun winning national championships," said Rupp, who won silver at the London Games.

Shalane Flanagan had no trouble in the women's 10,000, winning by more than 30 seconds.

In other finals on Thursday, Omar Craddock and Andrea Geubelle took home triple jump titles, while Brittany Borman won the javelin.

The women's 100 lacked some star power as world champion Carmelita Jeter was out with a sore right quadriceps and Allyson Felix skipped the race to save energy for the 200. Barbara Pierre won in 11.18.

For Jeter, there's a safety net, with an automatic spot at worlds reserved for her courtesy of her win in 2011. Given that, her coach, John Smith, said there's no reason to take any chances. He feels confident Jeter will be ready to defend her title in Moscow in August, provided she backs off the throttle now.

The 33-year-old Jeter captured three medals at the London Olympics, finishing third in the 200, second in the 100 and helping the 400-meter relay team to gold.

"When she goes out, she wants to win everything," Smith said. "When you are nursing yourself back to real good form, you have to be really mindful of where you are within your running."

Felix sat out simply to be ready for the 200, by far her stronger event.

A year ago at the Olympic trials, Felix was in the middle of some drama when she and training partner Jeneba Tarmoh finished tied for third in the 100, with only three women allowed to represent the country in London. Caught without any rule governing that sort of result, USA Track and Field scrambled to come up with a way to break the tie, with the athletes eventually settling on a head-to-head sprint.

In the end, Tarmoh opted to withdraw from the run-off hours beforehand, giving the spot to Felix.

Tarmoh said there was nothing to prove at nationals this summer, only to run fast.

"New chapter," she said after finishing second in her preliminary heat to advance. "I just want to go out there and run fast and continue to progress in the 100."

One of the top performances of the night was turned in by a 17-year-old high school student, who didn't even win her heat. Mary Cain trailed training partner Treniere Moser most of the race and finished second to advance.

Cain is as effervescent off the track as she is on it. The first words out of her mouth after her finish were, "Of course, Moscow is on your mind."

A soon-to-be senior at Bronxville (N.Y.) High, Cain has been training for the past month in Park City, Utah, with members of the Nike Oregon Project, which also includes Moser, Galen Rupp and London Olympic gold medalist Mo Farah.

Cain's definitely holding her own in a group supervised by Alberto Salazar.

"She does not seem like the typical runner at all," Moser said. "If you meet her, she's worried about school and friends. In Park City, she wanted to go on the water slide and on hikes."

Cain is just confident enough to think she can make the world team, too.

"I've always shot for the stars," said Cain, who has set more than a dozen high school and American junior records so far this season.

LaShawn Merritt, the 2008 Olympic gold medalist, had no trouble advancing in the 400, while '04 Olympic champion Jeremy Wariner finished last in his heat and failed to move on.

For Sanya Richards-Ross, it was all about delicately getting around the track on her surgically repaired big toe. She did and will race again.

''It's a little bit excruciating," the 2012 Olympic champion said of her toe. "But time is not waiting for me so I have to go."