Olympics-Tennis-Britain's Murray tames Del Potro to retain title

RIO DE JANEIRO, Aug 14 (Reuters) - Britain's Andy Murray beat Argentina's Juan Martin del Potro 7-5 4-6 6-2 7-5 in a compelling and gruelling Olympic tennis final on Sunday to become the first player to successfully defend the title. World number two Murray deployed a precision defensive game which eventually wore down the towering Argentine's barreling forehand and powerful service game. Murray racked up his 18th successive singles win, a hot streak that also brought him a second Wimbledon title. (Reporting By Joshua Schneyer, editing by Ed Osmond)