Sprinting powerhouse the United States won their fifth straight women's Olympic 4x400m gold medal on Saturday, destroying the field to win by more than three seconds.
The strong US team, including individual 400m champion Sanya Richards-Ross and 200m winner Allyson Felix, won in 3min 16.87sec. Russia took silver in 3:20.23 with Jamaica (3:20.95) winning bronze.
Just a day after breaking the long-standing world record in the women's 4x100m relay, the US team seized the race by the scruff of the neck from the start.
Felix, running the second leg, opened up a gaping lead and by the time Richards-Ross took the baton on the anchor leg, the Americans were virtually home and dry barring a disaster.
It means a third gold medal of the Games for the versatile 26-year-old Felix, who is concentrating on the 100m and 200m this season after last year winning silver in the individual 400m at the world championships.
The 4x100m quartet, including Felix, on Friday sliced more than half a second off the 27-year-old record of 41.37sec set by the former East Germany in 1985, four years before the Berlin Wall fell.