Reigning 400m world champion Jerome Young will not run the event at the Olympics after failing to make the final at the US Trials.
Young celebrates his 400m world title last summer
Young, who faces being stripped of his 400m relay medal from the Sydney Olympics for a failed drugs test, could finish only fourth in his heat.
World silver medallist Tyree Washington will also miss out after he too failed to qualify for the final.
Earlier, Olympic champion Marion Jones missed selection for the 100m.
And her boyfriend Tim Montgomery, the world record holder, missed out in the men's version.