Usain Bolt led Jamaica to the 4x100 meters Olympic gold in a world record time on Saturday.
Bolt took on the baton with a one-meter lead and powered away from America's Ryan Bailey to cross the line in 34.84 seconds.
It was two tenths of a second inside the world record Bolt, Nesta Carter, Michael Frater, and Yohan Blake set at the world championships last year.
"It's always a beautiful feeling to end off like this," Bolt said.
"We did it last year in the world championships - for me it is a wonderful feeling."
On the fastest race in history, Bolt said: "The team came out and gave their all - I knew a world record was possible."
The American team of Bailey, Trell Kimmons, Justin Gatlin and Tyson Gay equaled the old world record for silver in 37.04.
"There was energy coming from the blocks and Tyson did a great job on the third," Gatlin said.
"We did it, we did a great job and next year we're going to do an even better race."
Trinidad and Tobago's quartet claimed the bronze in 38.12 after the third-placed Canadians were disqualified.
Bolt became the first sprinter to retain both sprint gold medals after winning the 100 and 200 meters races in London.
The relay gold marked a defence of all three titles.
