Andy Murray has been handed a tough opening test at the Olympics as he was drawn to face Stanislas Wawrinka in the first round.
Murray is looking to do better than his first-round defeat to Lu Yen-Hsun in Beijing four years ago, but world number 26 Wawrinka will pose a stern challenge for the Wimbledon runner-up.
The pair last met on grass at Wimbledon three years ago, when Murray beat Wawrinka in five sets.
World number one Roger Federer will face Alejandro Falla, which is a rematch of their 2010 Wimbledon epic where Federer came back from two sets down to defeat the Colombian in five sets.
Novak Djokovic, who is in the same half of the draw to Murray, will face Italy's Fabio Fognini.