America's world 100 metres champion Tyson Gay sensationally failed to make the Olympic final on Saturday.
The 26-year-old, who had been out for over a month with a hamstring injury, could finish only fifth in his semi-final which was won by Jamaica's Asafa Powell.
Gay, who suffered the injury at the US trials in early July, was expected to form one part of a three-way battle for the blue riband event along with Powell and world record holder Usain Bolt.
However, he looked to be already struggling in the second round on Friday and while he gave it his best in the semi-final he was just bested by team-mate Darvis Patton for the fourth and final automatic qualifying spot in the final.
Bolt was comfortably the fastest man in the first semi-final.