Jamaican sprint sensation Usain Bolt demolished his own world record, clocking a scarcely believable 9.58 seconds to win the 100m title at the world athletics championships on Sunday.

Defending champion Tyson Gay from the United States was second in a personal best of 9.71 and Bolt's countryman Asafa Powell was third in 9.84 as the top five finishers all ran under 9.94.

Coming into the championships it had seemed unlikely that Bolt would be able to match his extraordinary triple triumph in the 100m, 200m and 4x100m relay at last year's Beijing Olympics - all in record time.

But Sunday night's remarkable victory, where he slashed a huge 0.11 off his own world record, just about surpassed it.

Bolt started well in the final and had the field covered by the halfway mark before powering away.

He then treated the raucous crowd to his famous Lightning Bolt pose during a joyous victory lap at the Berlin Olympic Stadium.

"I said anything could happen and it did," said Bolt.

"It was a big target but I got 9.58 seconds and I'm really happy with myself.

"Now I plan to do even better in the future.

"I got a good start and that was my main aim and then my drive phase was good.

"When I got to 50 I knew it was going to be hard to get past me because that's the strongest part of my race.

"So I just ran to the line - overall it was a good race."

Bolt pocketed $US160,000 ($A190,000) for the victory and the world record.

The only nervous moment came when he false-started for the first time in his career during the semi-final - an incident he later put down to some light-hearted byplay with Antigua's Daniel Bailey.

Bolt and Gay are scheduled to again lock horns in the 200m and 4x100m relay later in the championships - although the American said a groin injury put his participation in the half-lap race in doubt.

"I did my best," said Gay after claiming the 100m silver medal.

"I put the race together as well as I can

"I had faith and I did the best I could."

Gay said he was pleased that Bolt had broken the world record as he had been telling people all year that it was possible to break 9.6 seconds.

Former world record holder Powell did well to claim the bronze medal after a largely disappointing year by his lofty standards.

"To come here and get third place I feel very proud," he said.

In other action on day two of the championships, New Zealander Valerie Vili continued her domination of the women's shot put, adding a second straight world title to her Beijing Olympic crown with a best throw of 20.44m.

Nadine Kleinert of Germany was second with 20.20m and China's Lijao Gong claimed the bronze medal with 19.89m.

Jessica Ennis claimed Britain's first-ever world heptathlon title, dominating the seven-discipline event to win with 6.731 points, the highest total in the world this year.