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BEIJING, CHINA - AUGUST 24: Isaac Makwala of Botswana reacts after competing in the Men's 400 metres semi-final during day three of the 15th IAAF World Athletics Championships Beijing 2015 at Beijing National Stadium on August 24, 2015 in Beijing, China. (Photo by Lintao Zhang/Getty Images for IAAF)

BEIJING, CHINA - AUGUST 24:  Isaac Makwala of Botswana reacts after competing in the Men's 400 metres semi-final during day three of the 15th IAAF World Athletics Championships Beijing 2015 at Beijing National Stadium on August 24, 2015 in Beijing, China.  (Photo by Lintao Zhang/Getty Images for IAAF)