EUGENE — It took Tyson Gay only 9.75 seconds to prove that, yes, he’s healthy, and leave the rest of the track world wondering — and maybe worrying — about what he might do next.

With a helping wind at his back, America’s best-known sprinter ran his 100 preliminary heat in the seventh-fastest time under any conditions Thursday, then exited stage right, not to be seen again at the U.S. championships.

About a half hour after he ran, Gay’s coaches confirmed he wouldn’t be racing again this week.

“But I want to,” Gay said. “Because I ran a horrible race.”

Probably not what the competition wants to hear.

Already qualified for this summer’s world championships in Berlin, Gay used this single race at nationals as a tune up. Because of the wind, the 9.75 won’t go down as the new American record, even though this was .02 seconds faster than the mark he set last year on the same track.

Record or no, over the past four weeks, Gay has made his point: He’s ready to take on world-record holder Usain Bolt.

Combine this with the 19.58 he clocked in the 200 in May in New York — only the third sub-19.6 ever in that event — and it’s clear Gay is over whatever ailed him last year when an injury in the 200 at Olympic trials, also on the same track in Eugene, derailed his season. Was he trying to send a message?

“Not necessarily to anybody in particular, but more for myself,” he said. “I knew it was wind-aided, so of course it doesn’t go into the books. But at the same time, it still lets me know that my legs are ready to turn over faster. They’re a lot faster when I execute the beginning part.”

Before Gay’s run, the women took to the track and everything went to form, with Allyson Felix, Muna Lee, Lauryn Williams, Carmelita Jeter and Torri Edwards all advancing today’s 100-meter semifinals.

Olympic champion LaShawn Merritt cruised to a win in 45.23 seconds in his 400 prelim, which was missing Jeremy Wariner, who also has a bye into worlds. Wariner will run in the 200 later this week.

Sanya Richards (400) and Lopez Lomong and Alan Webb (1,500) were among the other big names who advanced easily.

Stephanie Brown Trafton added a national title to the Olympic gold medal she won last year in discus. Amy Yoder Begley outkicked Olympic bronze medalist Shalane Flanagan at the end of the women’s 10,000 for a mild upset and Galen Rupp, a University of Oregon hometown favorite, blew away Dathan Ritzenhein over the last 600 meters for a 6-second victory in the men’s 10,000.