David Rudisha of Kenya won the men's 800 metres Olympic title here on Thursday in a stunning new world record of 1min 40.91sec.
The 23-year-old world champion was five metres clear of Nijel Amos of Botswana after taking control of the race from an early stage and charged down the home straight at the capacity crowd rose to their feet.
Amos timed 1:41.73 - a world junior record, to win Botswana's first ever Olympic medal in athletics while another Kenyan Timothy Kitum took the bronze in a personal best of 1:42.53.
It was the first world record in an 800 metres Olympic final since Cuba's Alberto Juantorena set the mark in the 1976 final.
"To come here and break the world record is something unbelievable," said Rudisha.
In what was probably overall the fastest 800m race of all time, seven of the eight finalists set personal bests -- Andrew Osagie's eighth-place time of 1:43.77 would have been good enough for gold in the 2008 Olympic final.
Rudisha, who was already the world record holder with 1:41.01 set two years ago, set the pace from the start with Abubaker Kaki of Sudan and Mohammed Aman of Ethiopia in close pursuit.
However, heading down the back stretch he kicked once and had Kaki and Aman struggling to stay in the hunt and another kick at the 300 metres mark had them fighting for the minor medals.
Amos surged into second on the bend into the straight and fought gamely to reel in the Kenyan but in the end he settled for his historic silver.