Gold medalist Andy Murray (GBR) of Britain reacts after receiving his medal in men's singles tennis final during the Rio 2016 Olympics in Brazil, Aug 14, 2016. [Photo/Agencies]

RIO DE JANEIRO - Britain's Andy Murray beat Argentina's Juan Martin del Potro 7-5 4-6 6-2 7-5 in a compelling Olympic tennis final on Sunday to become the first player to win two men's singles gold medals.

The world number two and his Argentine opponent shared a long hug at the net, with both man trying to hold back the tears, after a punishing, see-sawing, four-hour contest played out in front of a boisterous crowd at the Olympic Tennis Centre.

Murray's consistency proved decisive. He was able to wear down Del Potro's weaker backhand and frequently drew the fatigued Argentine into the net with deftly placed drop shots as the contest wore on.

Del Potro served for the fourth set at 5-4 but Murray broke the Argentine in consecutive games to claim the match, his 18th straight victory following his second Wimbledon title in July.

The 29-year-old Scot, winner of three grand slams, called the Rio encounter "one of the hardest matches I've had to play for a big title."

"There were so many ups and downs in the match... this has been much harder than London," he told reporters in reference to his gold medal win four years ago.

The Scot, Britain's flag-bearer at the opening ceremony in Rio, had been a hot favorite to retain his title but he was pushed all the way by an impressive Del Potro, who was roared on by hundreds of passionate Argentine fans.

TREMENDOUSLY TIRED

Del Potro had blown open the tournament by beating top seed Novak Djokovic in the first round and then edged Rafa Nadal in a three-hour semi-final contest but the exploits had left him exhausted. Against Murray, he said he was dizzy and felt close to passing out.

"I left the last of my toenails on the court," said Del Potro, whose ranking has slipped to 141 after a series of wrist injuries over the past six years.

"I was tremendously tired. It was the crowd that made me keep running."

The 2009 U.S. Open champion, whose route to the final included being stuck in an Olympic village elevator for 40 minutes before his first round win, claimed his second Olympic medal after a bronze at the 2012 London Games.

His blistering forehand produced several winners but said he had no complaints about the final result, crediting Murray for playing "smarter" tennis at crucial moments.

Murray said he might seek a third title at the Tokyo Games in 2020, but acknowledged that his best playing days might be behind him by then.

Japan's Kei Nishikori, who will still be in his prime at his home Olympics, secured a bronze medal in Rio by beating Nadal 6-2 6-7(1) 6-3 on Sunday.