The world championships 100 meters cast played their parts to perfection Saturday as Usain Bolt and Tyson Gay took center stage, backed up by a comedy cameo from Asafa Powell and Dwain Chambers as villain. Everything remained on course for a Sunday night showdown (19.35GMT) after an entertaining opening day in perfect sunny conditions at the Olympic Stadium. There were gold medals for Russian Valeriy Borchin in the 20km walk, Kenyan Linet Masai in a spectacular women's 10,000 meters and American Christian Cantwell after an unusually gripping men's shot competition. The main draw, however, was the 100m and the crowd were given a glimpse of the power purring under the bonnets of the big names as they cruised through while still, in the case of Gay and Powell, breaking 10 seconds. Olympic gold medallist and world record holder Bolt was relaxed as ever in his evening second round, exchanging smiles with Daniel Bailey from Antigua before following him over the line in 10.03. Gay, the defending champion, clocked 9.98 but said his groin injury was still troubling him. Former world record holder Asafa Powell clocked the fastest time of the day with 9.95 but was somewhat lucky to still be involved after a morning error. Powell, who has earned the tag of “championship choker” after often failing to deliver on the big stage, eased up too much in his heat and had to scramble through in third, avoiding elimination by 200ths of a second. Briton Chambers, who served a two-year drug ban from 2003, shrugged off boos from the crowd to win his heat in 10.04. The withdrawal of double defending champion Tirunesh Dibaba opened up the 10,000 meters but nobody could have predicted what a fantastic race would result. It was a familiar enough scene of East African domination at the bell as three Ethiopians and two Kenyans went through in a bunch but Masai looked out of it when she slipped to third with 250 meters to go. Meselech Melkamu blasted through and thought she had won it, raising both arms in celebration as the long-striding Masai caught her on the line to win by a 10th of a second in 30:51.24. The Ethiopians, who had won the last five world titles, had to settle for silver and bronze. Things were much more straightforward in the walk as Borchin hit the front shortly after the midway point and drove clear in the final 5km to win in one hour, 18 minutes, 41 seconds. China's Hao Wang, who turns 20 on Sunday, took silver and Edgar Sanchez claimed bronze for Mexico in the event raced entirely in the city and finishing at the Brandenburg Gate. Cantwell's success made it seven golds from the last eight in the shot for the United States but he needed a fifth-round 22.03 throw, the best of the season, to overhaul Poland's Olympic champion Tomasz Majewski. Ralf Bartels gave the home crowd something to cheer when he took bronze. After the first four events of the heptathlon Briton Jessica Ennis led with 4,124 points. Ennis, Britain's strongest hope for a gold, started with the field's fastest 100 metres hurdles and best high jump and produced a personal best 14.14 meters in the shot. She ended with a season's best 200m to top the rankings in that event as well and set herself up for an assault on gold on Sunday, when, in addition to the men's 100m, the women's shot will also be decided. Pole vault favorite Yelena Isinbayeva, the world and Olympic champion and world record holder, remained in her tracksuit for most of the near-three hours of qualifying before joining the fray at 4.55 meters and sailing over.