Nicolas Massu collected a second gold medal of the Games when he followed up Saturday's men's doubles victory by beating Mardy Fish in the singles.
Name: Nicolas Massu
World ranking: 14
Career wins: ATP Tour titles in Amersfoort, Palermo, Kitzbeuhel and Buenos
After joining Fernando Gonzalez to earn Chile's first Olympic title in the early hours of Sunday, he dug deep to deliver another just 13 hours later.
Tired Massu, seeded 10th, took the first set 6-3, as unseeded American Fish made a string of unforced errors.
Fish took the next two sets 3-6, 2-6 but Massu hit back 6-3, 6-4 to win.
"I don't know how I did it. These are the best two days of my life," said Massu.
"I can't believe it. When I lost that third set set I thought I was going to lose the match because I couldn't move.
"But I got a second life. It's just too much, two gold medals in two days. It's unbelievable for my country."
Bleary-eyed Massu was clearly fatigued after his fifth-set marathon doubles success against Germany's Nicolas Kiefer and Rainer Schuettler.
That three-and-a-half-hour epic had only ended at 0040BST on Sunday and after the medal ceremony and a mandatory dope test, Massu only managed to get to bed at 0430.
The singles final began at 1730, but he took his time between points and had a massage on his left leg at end of the fourth set and somehow managed to see his way through another five-set thriller which lasted four hours.
Fish's faltering start allowed Massu to break in the second and fourth games and race to a 5-0 lead.
Fish held his serve in the sixth and eighth games and in between broke Massu in the seventh to reduce the Chilean's advantage to 5-3.
But Massu finally served out for the first set in the ninth game with two set points to spare.
The second set was a tight affair, with both players holding serve until the eighth game when Fish broke.
That gave the American the impetus he needed to go on and take that set and the next.
But just when Massu looked down and out he fought back to take the fourth set on the stroke of three hours.
The fifth set was a nail-biter with both players losing their two opening service games.
But as the pressure mounted the mistakes crept back into Fish's game and Massu quickly took advantage and went on to seal the match.
"He just kept getting better and better," said Fish afterwards. "And more untired."