Defending champion Usain Bolt ran 9.96 seconds as he won the seventh and final 100 meters heat at Beijing National Stadium on Saturday.
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Justin Gatlin also won his heat to qualify for Sunday's semifinals, but the American's time of 9.83s was wind-assisted.
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Gatlin's U.S. teammate Trayvon Bromell set the fastest non-assisted time of 9.91 as the 20-year-old debutant also won his heat. He will face Olympic champion Bolt in the opening semi.
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Bolt's fellow Jamaican Asafa Powell (right) also went through along with China's Bingtian Su (left) but Japan's Kei Takase (center) missed out.
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Mo Farah successfully defended his men's 10,000 meters title.
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The British runner will seek to follow up his double from the last world championships in 2013 by winning the 5,000m gold -- the heats start on Wednesday.
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Ghirmay Ghebreslassie made history by winning Eritrea's first gold medal at a world championships and, at the age of 19, becoming the youngest men's marathon titleholder.
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Germany's Christina Schwanitz won the other gold on offer on Saturday with victory in the women's shot put, taking a step up from her 2013 silver.
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The opening ceremony was on a much smaller scale than that of Beijing's 2008 Olympics, which cost a reported $100 million.