Watch: Tearful Andy Murray shares lovely moment with Juan Martin Del Potro after clinching Olympic Gold
Andy Murray was tired and emotional but victorious after coming through one of the hardest matches of his career to write his name into Olympic history.
The 29-year-old defeated brave Juan Martin Del Potro 7-5 4-6 6-2 7-5 to become the first tennis player ever to win two Olympic gold medals in singles.
To add to his achievement, Murray did it back-to-back, retaining the title he won so brilliantly on Wimbledon's Centre Court four years ago.
It is Murray's misfortune, although he would not put it in such terms, to be playing in an era where three all-time greats of the game have dominated the biggest prizes.
Watch the moment Murray won and shared a touching moment with Del Potro here:
Both competitors were in floods of tears at the end:
But out of Roger Federer, Novak Djokovic and Rafael Nadal, only the latter has an Olympic gold in singles.
Murray insisted he should not now be considered above the trio by any measure, saying: "I don't think I am but I know the fact it's not been done before means it's a very difficult thing to do. I'm very proud to have been the first one to have done that.
"It hasn't obviously been easy because a lot can happen in four years. Since London I've had back surgery, I've gone through some tough times on the court as well.
"I'm happy that I'm still here competing for the biggest events and I'll try and keep going."
Del Potro stood on the bottom step of the podium in 2012, while Murray soaked up the acclaim of Centre Court, but the Argentinian has spent half of the intervening four years trying to recover from a wrist problem that required three operations.
At one stage he doubted he would ever make it back and this run, with victories over Djokovic and Nadal, has again shown how much he brings to the sport, but there was to be no fairytale ending.
So weary was Murray when Del Potro's final backhand landed in the net that he could barely raise his arms above his head and he engaged in a long, emotional hug with his opponent at the net at the end of a night neither will ever forget.
Del Potro had the majority of a raucous crowd behind him and a huge heart but ultimately not the legs to defeat Murray.
Beating the Scot has become an increasingly difficult thing to do. No one has managed it since Djokovic in the French Open final two months and 18 matches ago.
Del Potro's ferocious forehand had been good enough to beat Nadal in an epic semi-final but Murray, although he did not serve well, is a master of exploiting an opponent's weaknesses.
In Del Potro's case it is his sliced backhand, with his wrist problems having robbed him of the confidence to play his two-hander consistently.
It stood up remarkably well but Murray prodded and probed and eventually broke him down, after four hours and two minutes of brutal, sometimes brilliant tennis.
The fourth set was a match in itself, with Murray three times coming from a break down after Del Potro had gone from the verge of total exhaustion to looking like he might force a decider.
"It means a lot," said Murray, his eyes red from tears.
He had begun the Games by carrying the flag at the opening ceremony and now here he was watching it being hoisted in his honour.
"Getting to carry the flag at the opening ceremony was an amazing experience and I was very honoured. I found that quite emotional," he added.
"I had to regroup and get my mind on the matches so, to finish it with a match like that, obviously I was fairly emotional at the end. It's been a build-up of emotions over the last 10 days and (I'm) just very happy that I got over the line tonight.
"It was one of the hardest matches I've had to play for a big title. The US Open I played with Novak to win my first slam was very hard but tonight I found really difficult emotionally. Physically it was hard, there were so many ups and downs in the match."
In the relentless world of tennis, Murray was not even able to take one night to celebrate his gold medal, instead joining Nadal in flying on a private jet to Miami - if he made it on time - ahead of next week's Masters tournament in Cincinnati.
But the world number two had time to pay tribute to Del Potro. Murray continued: "He's done amazing to get back to playing and competing at this level again after all of the issues that he's had with his wrists.
"Mentally I can only imagine how frustrating that must have been to keep going through the same problem and having to try and come back. He deserves a lot of credit and he should be very proud."