2016 Rio Olympics - Athletics - Preliminary - Men's 4 x 400m Relay Round 1 - Olympic Stadium - Rio de Janeiro, Brazil - 19/08/2016. David Verburg (USA) of USA (R), Javon Francis (JAM) of Jamaica (C) and Machel Cedenio (TTO) of Trinidad and Tobago run the final leg of the race. REUTERS/Lucy Nicholson

2016 Rio Olympics - Athletics - Preliminary - Women's 4 x 400m Relay Round 1 - Olympic Stadium - Rio de Janeiro, Brazil - 19/08/2016. Novlene Williams-Mills (JAM) of Jamaica leads the race. REUTERS/David Gray

2016 Rio Olympics - Athletics - Preliminary - Women's 4 x 400m Relay Round 1 - Olympic Stadium - Rio de Janeiro, Brazil - 19/08/2016. Competitors pass their batons for the third leg of the race. REUTERS/Lucy Nicholson

Jamaican Olympic gold medallist Usain Bolt poses with youths at the Mangueira slum Olympic center, ahead of the "Mano a Mano" challenge, a 100-meter race, in Rio de Janeiro, Brazil, April 16, 2015. REUTERS/Ricardo Moraes/File Photo

Jamaican Olympic gold medallist Usain Bolt (C) runs with youths at the Mangueira slum Olympic center, ahead of the "Mano a Mano" challenge, a 100-meter race, in Rio de Janeiro, Brazil, April 16, 2015. REUTERS/Ricardo Moraes/File Photo

2016 Rio Olympics - Golf - Men's Individual Stroke Play - Olympic Golf Course - Rio de Janeiro, Brazil - 13/08/2016. Thomas Pieters (BEL) of Belgium watches his tee shot on the ninth hole during the third round of the men's Olympic golf compeititon. REUTERS/Andrew Boyers FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. - RTX2KK1G

2016 Rio Olympics - Athletics - Final - Women's 400m Hurdles Final - Olympic Stadium - Rio de Janeiro, Brazil - 18/08/2016. Dalilah Muhammad (USA) of USA reacts after winning the race REUTERS/David Gray

2016 Rio Olympics - Athletics - Final - Women's 400m Hurdles Final - Olympic Stadium - Rio de Janeiro, Brazil - 18/08/2016. Dalilah Muhammad (USA) of USA celebrates after the race. REUTERS/Phil Noble TPX IMAGES OF THE DAY