Great Britain claimed a third gold medal in as many days in the Olympic Velodrome as their women's team pursuit quartet again lowered the world record with a sensational final display.
The battle for gold between GB and the United States had been much anticipated, after the two teams combined to break the world record on three occasions during qualifying.
However, the US had no answer to their opponents in the final as Laura Trott, Joanna Rowsell Shand, Elinor Barker and Katie Archibald broke new ground with a remarkable time of four minutes and 10.236 seconds, shaving almost two seconds off the previous best.
The silver medallists were ahead early on, but finished 2.218secs back after failing to keep pace when Britain turned up the heat from the 1500m mark.
Trott is the first British woman to win three Olympic golds and could yet earn a fourth in the omnium event.
Canada took bronze in the women's team pursuit, while Saturday's other final saw Elis Ligtlee triumph in the women's keirin, the Dutchwoman edging out Britain's Becky James and Anna Meares of Australia in a thrilling finish.
Meares now has six Olympic medals, gained across four Games.