Novak Djokovic (R) of Serbia and Rafael Nadal of Spain play an exhibition tennis match at a court set up on the deck of a ship, as the Perito Moreno glacier is seen in the background, near the Patagonian city of El Calafate. Djokovic and Nadal are in Argentina to attend a farewell event today for Argentina’s David Nalbandian, who is retiring from professional tennis.