LONDON, England (CMC) — The first man to ever run below 20 seconds in the 200 metres believes if Usain Bolt improves his start, he could break the nine-second and the 19-second barriers in the 100 and 200 metres respectively.

American Tommie Smith, who won the 200m in 19.83 seconds at the 1968 Summer Olympics in Mexico City, said once Bolt got a start similar to that of his training partner and fellow Jamaican Yohan Blake, both current world records would be under threat.

Bolt holds the 100m world record with a clocking of 9.58 seconds at the Berlin World Championships three years ago, and the 200m record with a time of 19.19 at the same showpiece event.

"If he gets a Blake start, we are looking at 8.9, 8.88, three eights in the 100 metres," Smith said Tuesday.

"If he gets a Blake start in the 200 and comes off the turn with that technique of his, he might really go sub-19."

The 25-year-old Bolt has had troubles with his start throughout his career, but has traditionally used his top-end speed to his advantage.

However, in the Jamaica Olympic trials two weekends ago in Kingston, he was punished for a bad start, losing to Blake in the 100 metres despite a swift finish.

Bolt was also dealt a second defeat in the 200m, again at the hands of the impressive Blake.

Smith said his style had been similar to that of Bolt's, but conceded that the reigning Olympic 200m champion's power outstripped everything else.

"I thought I was great when I ran. I didn't have the start and I didn't have the power," said Smith

"My average speed was quite close to Usain Bolt's speed. But he gained his full speed I would say five metres, six or seven strides sooner than I did. He's so powerful that he can get full speed 40 metres out in the 100, 120 metres of the 200.

"He's taller than me and more powerful. It scares you."