Monica Puig of Puerto Rico in action against Victoria Azarenka of Belarus during their second round match at the Miami Open tennis tournament on Key Biscayne, Miami, Florida, USA, 25 March 2016. EPA/RHONA WISE

Kyle Edmund of Great Britain in action against Novak Djokovic of Serbia during their second round match at the Miami Open tennis tournament on Key Biscayne, Miami, Florida, USA, 25 March 2016. EPA/RHONA WISE

Alexandr Dolgopolov of the Ukraine in action against Andreas Seppi of Italy during a match at the Miami Open tennis tournament on Key Biscayne, Miami, Florida, USA, 26 March 2016. EPA/ERIK S. LESSER

Heather Watson of Britain reacts against Yanina Wickmayer of Belgium during their third round match at the Miami Open tennis tournament on Key Biscayne, Miami, Florida, USA, 26 March 2016. EPA/ERIK S. LESSER

Andrey Kuznetsov of Russia in action against Stan Wawrinka of Switzerland during their second round match at the Miami Open tennis tournament on Key Biscayne, Miami, Florida, USA, 26 March 2016. EPA/ERIK S. LESSER