2016 Rio Olympics - Swimming - Final - Women's 800m Freestyle Final - Olympic Aquatics Stadium - Rio de Janeiro, Brazil - 12/08/2016. Katie Ledecky (USA) of USA competes on her way to winning the gold and setting a new world record. REUTERS/Stefan Wermuth TPX IMAGES OF THE DAY

2016 Rio Olympics - Swimming - Final - Women's 800m Freestyle Final - Olympic Aquatics Stadium - Rio de Janeiro, Brazil - 12/08/2016. Katie Ledecky (USA) of USA reacts after winning and setting a new world record. REUTERS/Marcos Brindicci TPX IMAGES OF THE DAY

2016 Rio Olympics - Swimming - Final - Men's 100m Butterfly Final - Olympic Aquatics Stadium - Rio de Janeiro, Brazil - 12/08/2016. Joseph Schooling (SIN) of Singapore competes on the way to winning the gold medal. REUTERS/Athit Perawongmetha

2016 Rio Olympics - Swimming - Final - Men's 100m Butterfly Final - Olympic Aquatics Stadium - Rio de Janeiro, Brazil - 12/08/2016. Joseph Schooling (SIN) of Singapore celebrates winning the gold medal. REUTERS/Stefan Wermuth

2016 Rio Olympics - Tennis - Victory Ceremony - Men's Doubles Victory Ceremony - Olympic Tennis Centre - Rio de Janeiro, Brazil - 12/08/2016. Rafael Nadal (ESP) of Spain and Marc Lopez (ESP) of Spain pose with their gold medals. REUTERS/Toby Melville

2016 Rio Olympics - Tennis - Victory Ceremony - Men's Doubles Victory Ceremony - Olympic Tennis Centre - Rio de Janeiro, Brazil - 12/08/2016. Rafael Nadal (ESP) of Spain and Marc Lopez (ESP) of Spain pose with their gold medals. REUTERS/Kevin Lamarque

2016 Rio Olympics - Tennis - Victory Ceremony - Men's Doubles Victory Ceremony - Olympic Tennis Centre - Rio de Janeiro, Brazil - 12/08/2016. Gold medalists Rafael Nadal (ESP) of Spain and Marc Lopez (ESP) of Spain, silver medalists Florin Mergea (ROU) of Romania and Horia Tecau (ROU) of Romania, and bronze medalists Steve Johnson (USA) of USA and Jack Sock (USA) of USA pose with their medals. REUTERS/Kevin Lamarque

2016 Rio Olympics - Tennis - Victory Ceremony - Men's Doubles Victory Ceremony - Olympic Tennis Centre - Rio de Janeiro, Brazil - 12/08/2016. Steve Johnson (USA) of USA and Jack Sock (USA) of USA react after receiving their bronze medals. REUTERS/Kevin Lamarque FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS.