Rio de Janeiro: Britain's Andy Murray became the first player in history to win two consecutive gold medals in Olympic men's singles, downing Argentina's Juan Martin del Potro 7-5, 4-6, 6-3, 7-5 in a hard-fought match here. The intense match lasted more than four hours on Sunday, with both players -- who had also competed in the doubles tourney in Rio -- becoming steadily more tired and committing assorted unforced errors during the fourth set, reports Efe. The Scot -- the No.2 ranked tennis player in the world -- had won the gold in the event in London in 2012, beating Roger Federer in straight sets. Del Potro had won the bronze on that occasion, after being defeated by Federer in the semifinals. Murray went out in front by 4-1 in the first set on Sunday, but Del Potro, clearly the underdog but a real fighter and sensing a chance to pick off the Scotsman, fought back to 5-5, whereupon Murray held his serve and took the set. Del Potro prevailed in the second set, going ahead 2-0 and holding his lead all the way to the 4-6 conclusion. In the third set, the Argentine initially got to 2-2 but then - beginning to show his fatigue - allowed Murray to easily take four of the next five matches for the set. It was in the fourth set that both players truly began to feel the exhaustion taking over. Play stayed even, back and forth until it was 5-5, whereupon Murray managed to grab the final game after saving two break points. And finally, with the match in a tiebreak, Murray managed to win the second match point for the gold. The men's singles final is the only match at the Olympics that can go to a gruelling five sets. Earlier on Sunday, Nishikori had knocked off Spain's Rafael Nadal to garner the bronze medal.