Serena Williams of the US serves during the women’s third round match against Elina Svitolina of Ukraine of the Rio 2016 Olympic Games Tennis events at the Olympic Tennis Centre in the Olympic Park in Rio de Janeiro, Brazil, 09 August 2016. EPA/MICHAEL REYNOLDS

Serena Williams of the USA in action during the women’s third round match against Elina Svitolina of Ukraine of the Rio 2016 Olympic Games Tennis events at the Olympic Tennis Centre in the Olympic Park in Rio de Janeiro, Brazil, 09 August 2016. EPA/MICHAEL REYNOLDS

Serena Williams of the USA in action against Elina Svitolina of Ukraine in the women’s third round of the Rio 2016 Olympic Games Tennis events at the Olympic Tennis Centre in the Olympic Park in Rio de Janeiro, Brazil, 09 August 2016. EPA/MICHAEL REYNOLDS

Serena Williams of the US during the women’s third round match against Elina Svitolina of Ukraine of the Rio 2016 Olympic Games Tennis events at the Olympic Tennis Centre in the Olympic Park in Rio de Janeiro, Brazil, 09 August 2016. EPA/MICHAEL REYNOLDS

Elina Svitolina (L) of Ukraine is congratulated by Serena Williams of the USA after defeating the World No.1 in the women’s third round match of the Rio 2016 Olympic Games Tennis events at the Olympic Tennis Centre in the Olympic Park in Rio de Janeiro, Brazil, 09 August 2016. EPA/MICHAEL REYNOLDS