Jamaica's Usain Bolt has become the first man to win the Olympic sprint double for 24 years with his second world record in five days in Beijing.
Bolt, who casually shaved 0.03 seconds off his own record in winning the 100m title in sensational style on Saturday, clocked 19.30secs to break Michael Johnson's 12-year-old record of 19.32s.
The 21-year-old, who turns 22 tomorrow, made a brilliant start and was already well clear of the field coming into the straight.
But unlike the 100m final, where he began celebrating well before the line, this time he sprinted through the tape to initially stop the clock at 19.31s, a time that was swiftly rounded down to 19.30s.
Churandy Martina, of the Dutch Antilles, took silver in 19.82.
American Wallace Spearmon crossed the line in third place in 19.95 but was disqualified for running out of his lane and team-mate Shawn Crawford, who ran 19.96 was promoted to the bronze medal.
Britain's Christian Malcolm finished seventh in 20.40.
When Bolt set off on his lap of honour 'happy birthday' rang out over the tannoy.
Johnson had actually said earlier in the day that he felt his record would not be broken tonight, but that it was only a matter of time before he could "kiss it goodbye."
But Bolt had other ideas and the determination on his face was clear as he powered down the home straight before glancing anxiously at the clock as he crossed the line.
"In order to run 19.30 he has to run the curve better and hold his speed for longer," Johnson had added earlier. "I didn't think he would run 9.69, but I think he could have run 9.62 if he had run to the finish and tied up his shoes."
In the final event of the evening, Jamaica's Melaine Walker won gold in the 400m hurdles in a new Olympic record of 52.64s.
Walker powered off the final hurdle to finish comfortably ahead of American Sheena Tosta with Britain's Natasha Danvers putting an injury-plagued season behind her to snatch bronze.
Danvers was almost caught on the line by the fast-finishing Anastasiya Rabchenyuk of Ukraine and waited for confirmation from the giant scoreboard that she had held on to set a new personal best of 53.84.