Tennis player and gold medallist Monica Puig (2nd L) greets the crowd while riding on a bus with wrestler Jaime Espinal (L), President of the Olympic Committee of Puerto Rico Sara Rosario (2nd R) and athlete Javier Culson during a welcome ceremony in San Juan, Puerto Rico, August 23, 2016. REUTERS/Alvin Baez

Tennis - French Open Womens Singles Final match - Roland Garros - Serena Williams of the U.S. vs Garbine Muguruza of Spain - Paris, France - 04/06/16. Serena Williams congratulates Garbine Muguruza. REUTERS/Benoit Tessier

Tennis - French Open Women's Singles Final match - Roland Garros - Serena Williams of the U.S. vs Garbine Muguruza of Spain- Paris, France - 04/06/16 Muguruza reacts. REUTERS/Gonzalo Fuentes

2016 Rio Olympics - Tennis - Preliminary - Women's Singles Second Round - Olympic Tennis Centre - Rio de Janeiro, Brazil - 08/08/2016. Caroline Garcia (FRA) of France in action against Johanna Konta (GBR) of United Kingdom. REUTERS/Toby Melville

2016 Rio Olympics - Tennis - Preliminary - Women's Singles Second Round - Olympic Tennis Centre - Rio de Janeiro, Brazil - 08/08/2016. Kristina Mladenovic (FRA) of France in action against Madison Keys (USA) of USA. REUTERS/Kevin Lamarque

2016 Rio Olympics - Tennis - Preliminary - Men's Singles Second Round - Olympic Tennis Centre - Rio de Janeiro, Brazil - 09/08/2016. Benoit Paire (FRA) of France in action against Fabio Fognini (ITA) of Italy. REUTERS/Kevin Lamarque

San Francisco 49ers quarterback Colin Kaepernick stands on the field before their NFL pre-season football game against the Denver Broncos in San Francisco, California, U.S. August 8, 2013. REUTERS/Stephen Lam/File Photo

2016 Rio Olympics - Olympic Village - Rio de Janeiro, Brazil - 06/08/2016. Sports fans queue to buy tickets to Olympic events. REUTERS/Marcos Brindicci