The men's 100 metres at the 2009 World Championships in Athletics were held at the Olympic Stadium on August 15 and August 16. The two main contenders for the event were the reigning World Champion Tyson Gay and Usain Bolt, the reigning Olympic champion and world record holder. Gay entered the competition with a season's best of 9.77 seconds (an American record) while Bolt's season's best was 9.79 seconds. Four other competitors had broken the 10-second barrier during the last months before the World Championship: former world record holder Asafa Powell, Olympic finalist Churandy Martina and emerging sprinters Daniel Bailey and Mike Rodgers.