Bolt braces for competitive track worlds
The Associated Press Last Updated: Aug 22, 2011 12:05 PM ET 

Usain Bolt will put his famous "Who faster?" taunt to the test again at the world track and field championships in Daegu, South Korea.
So far, it has worked every time it has mattered most.
Ever since his stunning world records and gold medals in the men's 100- and 200-metre sprints at the 2008 Beijing Olympics and his repeat at the 2009 worlds in Berlin, the Jamaican sprinter has become a global sports superstar.