Key dates: Aug. 5, 100-meter final; Aug. 8, 110-meter hurdles final; Aug. 9, 200-meter final; Aug. 9, decathlon final; Aug. 10, 4x400 relay final; Aug. 11, 4x100 relay final; Aug. 12, marathon. Venue: Olympic Stadium Big story: Will Jamaicans dominate the sprints? Usain Bolt (above), who set world records in the 100, 200 and 4x100-meter relay in Beijing, lost both sprints to Yohan Blake in Jamaicas Olympic trials because of hamstring tightness and withdrew from an Olympic tuneup meet in Monaco. U.S. trials winner Justin Gatlin, back from a doping suspension, and American record holder Tyson Gay should challenge for gold in the 100. American Wallace Spearmon Jr. should push the Jamaicans in the 200. Top U.S. prospects: Aries Merritt, clocked in a world-leading 12.93 seconds three times in the 110-meter hurdles, and Jason Richardson, who has two sub-13 times. Ashton Eaton, who set a decathlon world record at the trials, could be joined on the medal stand by Trey Hardee. Galen Rupp could win a medal in the 5,000, perhaps the only U.S. top-three finish in a race longer than 400 meters. Hes also entered in the 10,000. Others to watch: South African 400-meter runner Oscar Pistorius will become the first double amputee to compete in the Olympics. Chinas Liu Xiang, the Beijing Olympic 110-meter hurdles champion, and world record holder Dayron Robles of Cuba highlight a superb field. In the 400 hurdles, Puerto Ricos Javier Culson is favored after recording four of the worlds top five times this season. Mo Farah, the 2011 world champion at 5,000 meters and second at 10,000, is among Britains top hopes for a track and field medal. Little-known fact: According to the Telegraph newspaper, 100-meter race starter Alan Bell had the same role when Bolt was disqualified for false-starting at last years world championships. Bell also started many youth races involving Sebastian Coe, head of the London Olympic Organizing Committee.