EUGENE, Ore. -- Head so still her ponytail barely bobbed, arms swinging in perfect sync, Allyson Felix glided smoothly around the track, looking as if she has been running the 400 all her life.
The big question: Will she run it at the world championships later this summer?
Felix already has a spot in the 200 at the worlds thanks to her 2009 title, but remains uncertain about whether she also will attempt to run the longer distance, where she would go in as America's newly crowned champion.
She held off Francena McCorory at the finish Saturday at U.S. championships, winning in 50.40 seconds to become the first woman to win national titles in the 100, 200, and 400 over a career. Debbie Dunn was third.
"I felt good throughout and I feel like I'm learning a lot, how my body feels throughout," Felix said.
The 200-400 double is not easy to pull off given all the rounds and the lack of recovery time between them.
That's why the decision for Daegu, South Korea, in late August remains a difficult one for Felix and her coach, Bobby Kersee.
"That's my biggest thing, the thing that makes it tough for me to decide," Felix said of the quick turnaround. "I'm not going to be as fresh going into the 200. That's the big deciding factor."
Especially since that's her signature event. She doesn't want fatigue to derail her shot at winning a fourth straight 200 title at worlds.
Kersee said he will put Felix through some practices this week, see how she reacts, then make a decision. He was very impressed with how she looked, especially coming down the homestretch of the 400. Even some of the best runners start flailing a bit at the end of the one-lap race. Felix barely looked like she was breathing hard.
"I don't want to be cocky, but I really think she's one of the best 400-meter runners in the world," Kersee said. "She'll kill me if I take the 200 away from her, so it's going to be easier to tell her she can't run the 400."
Going double the distance she normally runs, and fighting a strong wind in the back stretch, Felix seemed to get stronger as the race went along Saturday.
That's an encouraging sign.
While she's up in the air about going for the 200 and 400 at worlds, one of her top rivals has already pledged to try to do it.
Sanya Richards-Ross has an automatic bid in the 400, but needs to qualify in the 200. She advanced to the semis with a solid race at the shorter distance Saturday.
"I felt good. But I have to run faster than I did today to make the team," Richards-Ross said. "I'm up for the challenge."
Up-and-comer Tony McQuay of the University of Florida won the men's 400 by blowing past former Olympic and world champion Jeremy Wariner over the final 100 meters. Wariner faded but held off Greg Nixon for second.
The win over Wariner had McQuay making bold predictions for worlds.
"I want to break the world record. I've got my mind set on that," he said.
Lots of folks have for many years. In fact, Wariner has promised himself a new Ferrari should he ever break Michael Johnson's nearly 12-year-old record.
McQuay wasn't even close to Johnson's mark of 43.18 seconds on Saturday, finishing in 44.68.
And Wariner, running in lane 2, needed a late lean -- plus some decimal points -- to edge Nixon 44.971 to 44.978.
Wariner wasn't reading too much into this performance, admitting he was behind the collegiate runners at this stage in his training. McQuay was runner-up at the NCAA championships this month.
"They've had an indoor season and everything," Wariner said. "By worlds, I'll be perfectly fine."
Wariner may even have his top rival back on the track, too.
LaShawn Merritt, the reigning world champ, wasn't at nationals as he finishes up a 21-month suspension after testing positive for a banned substance used in an over-the-counter male enhancement product.
Merritt has a bye into the field at worlds, but USA Track and Field's policy stipulates an athlete needs to run in at least one event at nationals to compete. The board will meet after nationals to determine Merritt's status.
Felix will be among the headliners on the U.S. worlds team heading to South Korea, a squad that also includes newly crowned national champions David Oliver (110 hurdles), Lashinda Demus (400 hurdles), Derek Miles (pole vault), Matthew Centrowitz and Morgan Uceny (1,500 meters), Kara Patterson (javelin), Jessica Cosby (hammer throw), Marquise Goodwin (long jump) and William Nelson (steeplechase).
A watered-down version of the men's 200 field completed the first round Saturday. There was no Tyson Gay (hip) or Justin Gatlin (sat out after qualifying in the 100). Meanwhile, Wallace Spearmon, still dealing with a nagging Achilles tendon injury, didn't qualify for the next round. Shawn Crawford, the 2004 Olympic champion, had the fastest time, and Walter Dix, fresh off his 100 title, moved on, as well.
Carmelita Jeter, who won the 100 the night before, had the fastest time in the women's 200.