The win for Bolt brings him a step closer to his goal of winning a historic "triple-triple" combination; whilst South Africa's Wayde Van Niekerk smashes the 400m record.
Usain Bolt roared into Olympic history Sunday, capturing an unprecedented third consecutive 100 metres crown with a time of 9.81 seconds to confirm his place in the pantheon of the greatest athletes the world has ever seen.
The win took the sprinter a step closer to his goal of winning a historic "triple-triple" combination of gold in the 100m, 200m and the 4x100m relay in three consecutive Olympics.
Bolt said two more victories in the 200m and 4x100m relay this week would assure him of "immortality."
"Somebody said I can become immortal. Two more medals to go and I can sign off. Immortal," said Bolt after his win.
Although well short of his world record,Bolt meanwhile expressed satisfaction with his performance.
"It was brilliant. I didn't go so fast but I'm so happy I won. I told you guys I was going to do it," he said.
The 29-year-old Jamaican legend, competing in his final Olympics, powered over the line in 9.81sec, vanquishing drug-tainted American rival Justin Gatlin who took silver with Andre De Grasse of Canada claiming bronze.
Wayde smashes 400m record
South Africa's Wayde van Niekerk ran the fastest single lap in history to win the 400 metres gold medal in 43.03 seconds and break a 17-year-old world record at the Olympic Games on Sunday.
Running in lane eight, the 24-year-old world champion got off to a flier and was streaking clear on the back straight but he upped his pace even further in the second half of the race to better American Michael Johnson's 1999 mark of 43.18 seconds.
"I believed I could get the world record," Van Niekerk told reporters. "I've dreamed of this medal since forever. I am blessed."
Van Niekerk crossed the line a good five metres ahead of 2012 champion Kirani James and held his hands to his head in disbelief at his time before being embraced by the Grenadian, who took silver in 43.76.
LaShawn Merritt of the United States, the 2008 Olympic champion, claimed bronze in 43.85, the first time the top three had run under 44 seconds in an Olympic 400 final.
Johnson, who won back-to-back Olympic titles in the event in 1996 and 2000, was dumbfounded by the quality of Van Niekerk's finish.
"Oh my God! From lane eight, a world record," Johnson said on the BBC. "He took it out so quick. I have never seen anything from 200 to 400 like that."
Van Niekerk marked himself as the leading contender for Rio when he led home Merritt and James with an exceptional run to win gold at last year's world championships in Beijing, where the podium again all ran under 44 seconds.
This year, he became the first sprinter to run the 100m below 10 seconds, 200m under 20 seconds and 400m in less than 44 seconds before deciding to concentrate on the longest distance in Brazil.