EUGENE — Instead of checking off days, months and years, Justin Gatlin can measure his track career on a stopwatch again.

EUGENE — Instead of checking off days, months and years, Justin Gatlin can measure his track career on a stopwatch again.

After serving his time for a doping ban that crossed off a world-record and more from his resume, Gatlin returned to a big stage — winning his preliminary heat Thursday in the 100 at U.S. nationals and staying very much in the mix for a spot at world championships.

Gatlin finished in 10.08 seconds and will join 2007 world champion Tyson Gay, 2009 national champion Michael Rodgers and Olympic bronze medalist Walter Dix in the group of 18 vying for three spots on the U.S. world team today.

Coming off the track after his successful return to nationals, Gatlin sounded more like a contender than someone simply happy to be here.

"I'm not really shooting for a time. I'm shooting for a dominant place," Gatlin said.

The last time the world saw Gatlin at a major meet was back in 2006, when he was the defending Olympic champion — still being pitched as a fresh-faced answer to the myriad of doping problems that had consumed track and field in recent years. As it turned out, he was part of the problem. He tested positive for excessive testosterone and, after a long stretch of arbitration and court hearings, received an eight-year ban that was later reduced to four.

Looking fit but maybe a bit thicker than he did in his first go-round, the 29-year-old lined up in the outside lane, got off to a good start and barely beat out Darvis Patton for the win in the first of the night's five heats. Gatlin is the fourth-fastest American this season, and knows this comeback, which started at minor meets across Europe last August, isn't just a dream.

"Last year, I was more gracious and grateful," he said. "I felt like I was running for mayor or something like that, kissing babies, instead of being more focused and being that more cutthroat edge kind of guy."

Once, he was that guy.

In the days before Gay became America's best sprinter and Usain Bolt rewrote the record book, Gatlin tied the world mark of 9.77 seconds. That was in 2006, shortly before the doping case came to light. His record was wiped off the books and his reputation, in some corners, was sullied forever. Back this week at America's biggest track meet, he is racing without a sponsor. A number of European meet directors have declined to invite him to races.

But he is officially cleared to compete, and with two more good races, he can earn a trip to world championships, where spots are based on time, not reputation.

In the women's 100, Carmelita Jeter stayed dominant, winning her heat in a 10.88-second sprint that looked more like she was coasting. She has the world's best time this season at 10.70.

Also advancing were Marshevet Myers, whose 10.87 was 0.01 off a personal best, and Lauryn Williams, the 2004 Olympic silver medalist.

Allyson Felix began her quest for a possible 200-400 double at worlds by winning her heat in the 400 — her less-accomplished distance — in 51.79. Also considering a 200-400 double is Sanya Richards-Ross, who as the defending world champion in the 400 already has a spot on this year's U.S. team. She ran her prelim in 52.02 and might be shutting down the 400 to focus on the 200 this weekend.

Jeremy Wariner also advanced easily in the men's 400 with a time of 45.94.

In the 10,000, Galen Rupp won his third straight national title, finishing in 28 minutes, 38.17 seconds, while Shalane Flanagan won in 30:59.97, more than 16 seconds ahead of Kara Goucher, who gave birth nine months ago.

"I just wanted to come out and run hard and see who wanted to play at my pace," Flanagan said.

Other winners Thursday were Kibwe Johnson (hammer), Christian Taylor (triple jump), Jarred Rome and Stephanie Brown-Trafton (discus) and Michelle Carter (shot put).

On this day, though, Gatlin seemed to grab the most attention — thanks both to his future and his past.

"When people get accused of certain things and have to serve their time, I let them serve their time," said Shawn Crawford, a former workout partner. "But if you're a friend of mine before, you're a friend of mine after. I judge the heart. He's always been a genuine person to me. What I see here is consistent across the board."