Nick Smidt judged himself harshly after failing to qualify for the final of the 400m hurdles at the Olympics on Sunday.

The 24-year-old athlete still got off to a good start, but collapsed completely in the last part.

"I think I've had a really bad run and I feel like I've done myself a disservice and disappointed my family," he said with a lump in his throat and tears in his eyes.

Smidt was sure he could make it to the final, although he knew he would have to take a second off his personal best.

"I was mentally ready for it. I had been pumping myself up all day. Like: if you break a leg or a shoulder, it doesn't matter, you just go as hard as possible. You have the legs."

Smidt made a good comeback in his heat of the semi-finals to the last straight, but in the last meters he completely lost the rhythm and collapsed.

He crossed the finish line in 49.35 in seventh place.

It was his best season, but not a personal best.

"It was like the earth was sinking under me. I feel so stupid, as if it wasn't because of the competition that is better, but completely because I couldn't get through that acidification. I don't know why, but it touched me for a moment emotional."

Despite his disappointment, Smidt looked ahead again.

"In a few days I will look at it differently and I will be proud that I have been in the semi-finals of the Olympic Games. In three years it will be Paris. I will train hard for it."