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FILE - In this June 11, 2016, file photo, Usain Bolt, of Jamaica, wins the 100-meter final ahead of Yohan Blake and Asafa Powell, both of Jamaica, in the Racers Grand Prix track and field event at the National Stadium in Kingston, Jamaica. Even if fully fit, Bolt, the world record-holder and two-time defending champion in the 100- and 200-meter sprints, will have plenty of competition. in Rio. (AP Photo/Collin Reid, File)

FILE - In this June 11, 2016, file photo, Usain Bolt, of Jamaica, wins the 100-meter final ahead of Yohan Blake and Asafa Powell, both of Jamaica, in the Racers Grand Prix track and field event at the National Stadium in Kingston, Jamaica. Even if fully fit, Bolt, the world record-holder and two-time defending champion in the 100- and 200-meter sprints, will have plenty of competition. in Rio. (AP Photo/Collin Reid, File)