Czech Republic's Lucie Safarova (bottom R) and Czech Republic's Barbora Strycova return the ball to USA's Serena Williams (L) and USA's Venus Williams during their women's first round doubles tennis match at the Olympic Tennis Centre of the Rio 2016 Olympic Games in Rio de Janeiro on August 7, 2016. / AFP / Martin BERNETTI (Photo credit should read MARTIN BERNETTI/AFP via Getty Images)
