Allyson Felix won her second Olympic gold medal of the games and added a world record on top as she powered the US sprint relay team past its Jamaican rivals in the 4x100 meters.

The 200-metre champion ran a blistering second leg and 100 metre silver medalist Camelita Jeter finished off the world record job, pointing to the time clock with her mouth wide open as soon as she got past the line, seeing that the 27-year-old mark of the former East Germany was gone.

The US team finished in 40.82 seconds, shaving a massive 0.55 seconds off the old mark.

It was the second world record in as many days on the super-fast track of the Olympic Stadium after David Rudisha of Kenya set a mark in the 800 metres on Thursday.