Andy Murray's chances of winning a third straight Olympics title in the men's singles have been dashed by a quad strain. The Team GB star was champion at London 2012 and Rio 2016, becoming the first player to ever defend a singles title in tennis. Murray was due to start his campaign against Canada's Felix Auger-Aliassime on Sunday but after consulting with medical staff he was told not to compete in both the singles and doubles. The three-time grand slam winner started his doubles campaign alongside Joe Salisbury with an upset win over second seeds Nicolas Mahut and Pierre-Hugues Herbert on Saturday. Murray will continue his quest for a third Olympics gold alongside Salisbury. "I am really disappointed at having to withdraw but the medical staff have advised me against playing in both events," Murray said via a Team GB news release.