Olympic bronze medallist Walter Dix crashed out of the world athletics championships when he injured his right hamstring in the 100 metres semi-finals at the U.S. trials in Oregon.
Dix, who won 100 and 200 metres bronze at Beijing, finished a non-qualifying sixth in 10.32 seconds in the second semi-final.
He says he won't run the 200 metres at the U.S. trials.
That means the 23-year-old will not make the U.S. world championship team since only the top three finishers in the American trials and defending world champions qualify.
Olympic decathlon gold medallist Bryan Clay and 110 metres hurdles bronze medallist David Oliver also will miss the world championships in Berlin because of injuries.