Tyson Gay and Justin Gatlin cruised through the opening round of the 100 meters at the U.S. trials on Thursday as America's top sprinters launched their bids for August's world championships. Former world champion Gay, the year's fastest man, won his heat in 10.28 seconds while Olympic bronze medalist Gatlin, racing into a stronger head wind, finished behind collegian Charles Silmon in 10.37 in the next race. Silmon ran 10.35. "I didn't really have a great start," said Gay, his hair and beard neatly trimmed after several months of letting both grow out. "But (I wanted) to the get the kinks out, get the nerves out. I should be ready for tomorrow." Gatlin, who recently surprised world record holder Usain Bolt in Rome, was more concerned about qualifying than a fast time, especially with a 2.9 meters per second wind blowing into his face. "There was a little hurricane out there, the head wind, but it felt good to come out here and shake the legs out a little bit," said the 2004 Olympic 100 meters gold medalist. The semi-finals and finals are on Friday with the top three finishers from the Des Moines, Iowa, meeting qualifying for the August 10-18 worlds in Moscow. Collegian Dentarius Locke and Jeff Demps were the day's fastest, both in 10.19 seconds, as former U.S. champion Mike Rodgers and Olympian Walter Dix joined Gay and Gatlin in the semi-finals. Barbara Pierre, a former Haitian Olympian now representing the United States, led a depleted field in women's 100 meters qualifying. Pierre clocked 11.18 seconds as Olympic silver medalist Carmelita Jeter and fellow Olympian Tianna (Madison) Bartoletta missed the meeting through injury and Olympic 200 meters gold medalist Allyson Felix chose to run only her specialty. Jeter still advanced to the world championships thanks to her wild card entry as the defending world champion. Jeremy Wariner was not as fortunate. The 2004 Olympic winner finished last in 400 meters qualifying. Olympic silver medalist Galen Rupp claimed the men's 10,000 meters final, winning in 28 minutes, 47.32 seconds, two seconds ahead of runner-up Dathan Ritzenhein, with Shalane Flanagan, the 2008 Olympic bronze medalist, taking the women's race in 31:43.20. The championships continue through Sunday.