SYDNEY: Jamaican sprint superstar Usain Bolt hopes to lower his 100 metres world record from 9.58 to 9.4 seconds, a mark he believes would never be beaten, a report said on Wednesday.

However Bolt, in Sydney for 10-year anniversary celebrations of the 2000 Olympics, said bettering the time he set last year in Berlin was not an "obsession".

"That`s where the record is gonna stay," he told Sydney`s Daily Telegraph, referring to 9.4sec. "But it`s not an obsession. I already have the world record."

Bolt, a double world record-holder in the 100m and 200m and the Olympic and world champion in both events, also said he hoped to seal his legacy at London 2012.

"London is a very big stage for me because there are so many Jamaicans in London," he said. "It will change my career there. I`ll keep doing, but I`ll do something different."

Bolt is reportedly considering tackling the 400m and challenging American legend Michael Johnson`s 1999 record of 43.18sec.

BDST: 1543 HRS, SEPTEMBER 15, 2010