By Gene Cherry

EUGENE, Oregon, June 23 (Reuters) – Former Olympic champion Justin Gatlin took a confident step forward on his comeback trail, breezing through the first round of the men’s 100 meters in an eye-catching 9.90 seconds at the U.S. athletics trials on Saturday.

Gatlin, who won gold at the 2004 Athens Games but missed four years of competition between 2006 and 2010 due to a doping suspension, had no problem with the cold and wet weather as he topped the time-sheets.

“It really defines warriors, how well you can get up for it,” he said with a smile.

Tyson Gay and Walter Dix, expected to be his main rivals in Sunday’s semi-finals and finals, also advanced without fuss.

Gay, in only his second race in a year because of hip surgery, clocked exactly 10 seconds to win his preliminary with the day’s second fastest time.

“I was a little nervous with the start … but all and all it felt pretty good,” said the world’s second fastest man behind Jamaican Usain Bolt.

Olympic bronze medalist Dix also won his heat with a time of 10.03.

Despite the miserable weather, Ashton Eaton was closing in on a big decathlon score, having collected 8,189 points with one event remaining.

But Olympic champion Bryan Clay was out of the running after a poor showing.

Only the top three finishers in the trials qualify for London, and Clay stood 15th after problems in the hurdles and discus.

Reigning world silver medalist Danielle Carruthers and 2004 Olympic champion Joanna Hayes failed to make it past the semi-finals of the women’s 100 meters.

Two-times Olympic shot put silver medalist Adam Nelson, hampered by a groin injury, also missed a chance to make the U.S. team, finishing a non-qualifying 15th.

Former world champions Reese Hoffa and Christian Cantwell, and reigning global indoor winner Ryan Whiting led qualifying with Hoffa making the top throw of 21.22 meters.

The trials continue through July 1.