American sprint legend Michael Johnson believes that Jamaican sprinter Usain Bolt can lower his 100m world record time to 9.4 seconds from his current best of 9.58s.

Bolt set the 100m sprint world record at the Beijing Olympics in 2008 with a time of 9.69s then smashed it a year later in Berlin with the current 9.58s, but Johnson believes that the fastest man on the planet is capable of running as fast as he wants.

"If Usain was to be really focused and committed on cleaning up his technique he could probably run 9.4s," Johnson told Laureus.

"I think he can do whatever he wants to do. If he gets to the starting line healthy, at his best, everyone else at their best, he wins every time."

Bolt has pulled out of the final Olympics warm-up ahead of the London Games.