Bershawn Jackson has admitted that his run in the heat of the 400m hurdles was "bad from the beginning".
The American, who boasts a personal best of 47.30s, faded badly in the final stages and finished his heat in last place, but Jackson is adamant that his race was "very disappointing" from start to finish.
He told reporters: "It felt bad from the beginning. I tried to reach for the first hurdle. Once my race started, it was all bad. The first hurdle was too far away, I had to reach for it.
"I tried to regain my momentum and take my time for the first round, the race got so far away in front of me. I tried to pick up. When I picked up, I shortened my strides. I should have just stayed wide. I couldn't make 10. It's a disappointing race for me, very disappointing.
"I overcame so much the last few years and I just felt like this was the one. Training was going awesome. I don't know if I put too much pressure on myself because I really wanted to win, but it's a hard one to swallow."
Britain's Niall Flannery went through to the semi-finals after he finished second to Kerron Clement in his heat.
