Ireland's Paul Hession failed to make it out of the heats of the 200 metres at the Olympic Stadium.
The 29-year-old athlete finished fifth in 20.69 seconds in a race won at a canter by Jamaican Yohan Blake.
Hession, who was 0.17secs off the third spot he needed to progress, said: "It is a little bit disappointing.
"I was hoping to push closer to third or second in that race. There were some serious athletes in there. That doesn't mean I couldn't beat them, but it wasn't there.
"I was a metre away from where I needed to be to qualify."
Team-mate Fionnuala Britton ran a personal best of 15:12.97 in the heats of the 5,000m, but it was not enough to go through as she finished 10th.