Defending men's 100 metres champion Maurice Greene was eliminated from the world championships when he finished eighth in his semi-final.
The American, who had been seeking an unprecedented fourth world title, made a flying start but then faded and pulled up in the closing stages to cross the line in 10.37 seconds.
He limped from the track, favouring his left leg. "I got a great start. Then I felt my quad (quadriceps) muscle pop," said Greene. "I tried to go through with it but it got worse and worse. It's not a cramp. I won't be able to tell anything until tomorrow.
"It might be good. It might be bad. You never can tell."
"It's my thigh muscle. I'm just disappointed. Yesterday I was just cramping up from my calves but today it was my quad muscles."
Greene, 29, has dominated men's sprinting since he won his first world title in 1997. But he has been increasingly troubled by injury and looked nothing like the dominant figure of old on the European circuit this year.