Rio de Janeiro - Andy Murray became the first player to win two Olympic tennis singles gold medals on Sunday when he defeated Argentina's Juan Martin del Potro 7-5, 4-6, 6-2, 7-5 in an epic final.
Murray added the Rio title to his 2012 triumph and to his Grand Slam collection of the 2012 US Open and 2013 and 2016 Wimbledon crowns.
It also stretched the 29-year-old's current winning streak to 18.
The final will go down as one of the best in the Olympics, lasting over four hours and ending with both men embracing at the net.
"Today was a very up and down match, very stressful. Both of us had a lot of chances and, it was a long and tiring match. I'm just glad I managed to get through it," said Murray.
He ended with 10 aces and 46 crunching winners while del Potro smashed 39 winners but was undone by 57 unforced errors.
Del Potro, a bronze medallist in London four years ago, was inconsolable at the end, weeping as he sat courtside.
The Argentine has fought his way back to the top after undergoing three surgeries.
"What he's had to go through over the last three years or so with his wrists -- I can't imagine how mentally difficult that would have been, how frustrating that would have been for him," added Murray.
"To get himself back to playing at this level, fighting for the biggest events and competing against the greatest players in the world is an amazing credit to him. He should be very proud of his efforts."
Murray took a 5-2 career advantage over 2012 bronze medallist del Potro into the final and he was quickly in the ascendancy, breaking for a 2-0 lead.
Del Potro, who was pushed to the brink of retirement last year after undergoing the wrist surgeries, was slow out of the blocks.
That was hardly a surprise for a player who had defeated two of the top three seeds to make the final -- Novak Djokovic in the first round and then winning a three-hour epic to beat Rafael Nadal in Saturday's semi-finals.
But he soon found his range, breaking in the third game before handing the advantage straight back, allowing Murray to stretch out to a 4-1 lead.
Backed by vociferous Argentine support, all proudly sporting the sky blue and white shirts of their national football team, the 1.98m (6ft 6ins) giant clawed his back in the seventh game.
But Murray was the more assertive in the closing stages, claiming the opener in the 12th game on a second set point with a pinpoint, down-the-line backhand after 74 minutes on court.
Murray saved a break point in the first game of the second set with a sweet drop shot which del Potro was unable to reach despite a desperate scramble from the back of the court.
The 2009 US Open champion slumped, head down on the net for a few moments to catch his breath.
It did the trick as he soon unleashed a monster backhand to secure the break at the second opportunity.
The final was all level in the 10th game as del Potro converted on a fourth set point, shrugging off a time violation from umpire Pascal Maria.
The big Argentine was looking increasingly weary and he lost serve in the sixth game of the third set, allowing the British world number three to move ahead again, sealing the set with a cross-court forehand.
Del Potro fought valiantly on, breaking for 2-1 in the fourth set, courtesy of a close combat exchange at the net but lacking the stamina to back it up and Murray was soon on level terms at 2-2.
In a dramatic passage of play, the South American was another break to the good but faltered when he served for the set in the 10th game.
Murray saved two break points for a 6-5 lead.
In the dramatic conclusion, two Argentine fans were escorted out of the arena before Murray took victory on a second match point when del Potro netted a backhand.
Olympic tennis results on Sunday:
Gold medal final
Andy Murray (GBR) bt Juan Martin Del Potro (ARG) 7-5, 4-6, 6-2, 7-5
Bronze medal match
Kei Nishikori (JPN) bt Rafael Nadal (ESP) 6-2, 6-7 (1/7), 6-3
Gold medal final
Bethanie Mattek-Sands/Jack Sock (USA) bt Venus Williams/Rajeev Ram (USA) 6-7 (3/7), 6-1, 10-7
Bronze medal match
Lucie Hradecka/Radek Stepanek (CZE) bt Sania Mirza/Rohan Bopanna (IND) 6-1, 7-5