Usain Bolt produced an astonishing run of 9.72 seconds to break the 100 metres world record in New York last night, in only his fifth race at the distance.

The 21-year-old Jamaican lowered the previous best, held by compatriot Asafa Powell, by two one hundredths of a second at the Reebok Grand Prix meet at the Icahn Stadium.

Bolt, who won the silver medal in World Championship 200m last year, beat Tyson Gay into second place, although the American also ran a personal best of 9.85secs.

In May, the 6ft 5ins sprinter had signalled his intent, by running 9.76secs, the second-fastest 100m time in history, in Kingston, Jamaica. But after the race Bolt admitted he hadn't gone out to break the record.

"I wasn't looking for a world record but it was there for the taking so I just went out there and ran my best race," he said. "I had an idea [the record was on] because I ran in Trinidad and I ran pretty bad and still ran 9.92, so I was pretty confident coming here."

In the week leading up to the race Bolt has suggested he would specialise in the 200m in Beijing, but yesterday's performance has changed his mind.

"I think that would change now," Bolt said. "I'm definitely doubling up."