Usain Bolt doesn't have much more to prove. In the past week the Jamaican sprinter pulled off the unprecedented "double-triple," defending his gold medals in the 100-meter, 200-meter and 4x100 races.

But should Bolt be interested in quieting the doubters, there is a growing number of American football players who are expressing their belief that they could outrun Bolt. In a 40-yard race, at least.

Tennessee Titans running back Chris Johnson has doubted Bolt's supremacy for years. In fact, Johnson even tried to set up a race with Bolt in 2010. Unfortunately, no showdown ever happened.

After Bolt's impressive performance last week, Johnson repeated his claim that he would prove victorious in a 40-yard dash.

This weekend, Michigan quarterback Denard Robinson chimed in, saying that he thinks he could beat Bolt in a 40-yard dash as well.

"I've watched him run, and I'm pretty sure I can beat him in a 40-yard dash," Robinson said. "I'd get a better start, and I could take him."

Johnson probably has a more legitimate claim than Robinson. In 2008, Johnson ran a 4.24 at the NFL Combine, the fastest time recorded at that event. Meanwhile, Robinson ran a 4.32 in 2009.

And, really, how fast can someone be if he doesn't tie his shoelaces?

-- Follow Robbie Levin on Twitter @RobbieLevin.

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