50 worldwide contenders for 2012: Usain Bolt
Athletics (100m, 200m, 4x100m relay)
The peerless Jamaican has redefined sprinting since breaking the 100m world record in only his fifth competitive race over the distance. That was in June 2008, and Bolt has subsequently won the individual sprint double in world record times at both the Beijing Olympics and 2009 World Championships.
He believes he can lower the 100m record to a previously unthinkable 9.4 seconds.
Bolt cut short his 2010 season due to Achilles and back problems after suffering only his second 100m defeat - by Tyson Gay in Sweden.
He was disqualified from the 100m final at the 2011 World Championships after a false start but recovered to clinch gold in the 200m and sprint relay, the latter in a world record time.
His talent first came to global attention when he won 200m gold at the World Junior Championships at the age of 15. In 2004 he became the first junior athlete to break the 20-second barrier over the distance, but it was another three years before he earned his first senior medal - silver at the World Championships.
Did you know?
Bolt was born with scoliosis, a curvature of the spine that can cause back and hamstring problems and which has resulted in him having one leg shorter than the other.
The condition affected him at the Athens Olympics, when he failed to qualify from his first-round heat of the 200m, and the following year's World Championships in Helsinki, where he finished last in the final after pulling a muscle in the home straight. He makes several trips each year to Germany for treatment.