Donald Young of the US hits a return shot to Kevin Anderson of South Africa in their semi-final round Memphis Open tennis match at the Racquet Club of Memphis in Memphis, Tennessee, USA, 14 February 2015. EPA/TANNEN MAURY

Rafael Nadal of Spain in action against Pablo Cuevas of Uruguay during their match of the 2015 Rio Open tennis tournament in Rio de Janeiro, Brazil, 20 February 2015. EPA/MARCELO SAYAO

Donald Young of the USA reacts as he defeats Bernard Tomic of Australia in their quarter final round tennis match at the Memphis Open, at the Racquet Club of Memphis in Memphis, Tennessee, USA, 13 February 2015. EPA/TANNEN MAURY

Rafael Nadal, from Spain, returns to Brazilian Thomaz Bellucci during a first round game in the Rio Tennis Open 2015 in Rio de Janeiro, Brazil, 17 February 2015. EPA/Wagner Meier

Rafael Nadal, from Spain, serves to Brazilian Thomaz Bellucci during a first round game in the Rio Tennis Open 2015 in Rio de Janeiro, Brazil, 17 February 2015. EPA/Wagner Meier

Donald Young of the US hits a return shot to Denis Kudla of the US in their second round Memphis Open tennis match at the Racquet Club of Memphis in Memphis, Tennessee, USA, 12 February 2015. EPA/TANNEN MAURY