In front of a packed Olympic stadium in London, England, the man dubbed "the fastest human on the planet" took his last run around the track. Usain Bolt, 30, joined by his fellow countryman, raced in the 4x100m relay. With the sun setting on Usain's historic career, many wondered if "Lighting Bolt" could pull out one more victory to end things on a high note. Unfortunately, things did NOT go as planned. The gold medalist wasn't able to finish the race in a speedy fashion, having suffered a painful leg injury that left him lying on the track almost in tears. But like a true competitor, Usain did eventually limp his way to the finish line.