Justin Gatlin continues to be Team USA's top sprinter. Reuters

Justin Gatlin moved closer to a world sprint double and Allyson Felix broke through to win a stirring women's 400 meters at the U.S. trials for the world championships on Saturday.

Gatlin cruised through the 200 meters preliminaries in 19.92 seconds to move into Sunday's semi-finals and finals and a chance to face world record holder Usain Bolt of Jamaica in both the 200 and 100 at the worlds in Beijing in August.

He has a bye for Beijing in the 100 and did not run the event in Eugene.

But talk quickly turned to that race, where the U.S. will send a team of Gatlin, Tyson Gay, Trayvon Bromell and Mike Rodgers to the world championships.

"It is going to be hard to beat those guys," Gatlin said, knowing Bolt has not been at his best this year.

Olympic 200m champion Felix has a decision to make after running down Nastasha Hastings to win the U.S. 400 title in 50.19 seconds.

Hastings took second 50.25 and Phyllis Francis third in 50.67.

Francena McCorory, the year's fastest in the event, finished fourth in 50.88 and will miss the team unless Felix decides to run the 200 at the world championships.

Felix has a bye to Beijing in the shorter event and after her victory on Saturday is eligible to run either the 200 or 400 there.

A 400-200 double would be nearly impossible because of the schedule.

"I'll go down and sit with Bobby (Kersee)," Felix said of the upcoming decision. "I'm not sure what his time frame is but I'm sure we'll probably do it quickly. Ultimately, it's up to Bobby."

Felix tried the double under a more favorable schedule at the 2011 world championships, finishing second in the 400m and third in the 200m.

Asked if she had unfinished business in the 400m, Felix replied: "I feel like I still haven't reached my potential there. I feel like I could challenge myself there.

"But I still love the 200."

Dawn Harper-Nelson, the London Olympic silver medalist, beat a high quality field in the women's 100m hurdles, running

12.55 seconds to nip collegian Keni Harrison by a hundredth of a second.

Sharika Nelvis, who had run the year's top time of 12.34 in Friday's heats, claimed the final spot for Beijing in 12.59.

Former world champion Tianna Bartoletta added another season's best in the women's long jump, leaping 7.12 meters to outdistance Olympic champion Brittney Reese (6.97m).

The trials end on Sunday with the top three finishers in each event qualifying for the world championships.

(By Gene Cherry; Editing by Andrew Both)