Olympic officials are reporting that US athlete Manteo Mitchell ran the first leg of the 4X400m relay on a broken leg.
The USA finished joint fastest qualifiers for the final with The Bahamas in 2:58.87.
Mitchell, 25, will not participate in the final after an X-ray confirmed he had broken his left fibula bone during his run.
According to the London 2012 website, Mitchell said three days ago, he was going up the stairs in the Olympic Village when he missed his step and landed awkwardly.
I got treatment and I was fine, he said.
I did work-outs and when I warmed up today I felt really well, he said.
Mitchell said he got out pretty slow, but picked it up and when he got to the 100m mark and had an unusual feeling.
As soon as I took the first step past the 200 metre mark I felt it break. I heard it. I even put out a little war cry, but the crowd was so loud you couldn't hear it. I wanted to just lie down. It felt like somebody literally just snapped my leg in half, he said.
Mitchell said he knew if he finished strong the US could still get the baton around.
I saw Josh Mance motioning me in for me to hand it off to him, which lifted me. I didn't want to let those three guys down, or the team down, so I just ran on it. It hurt so bad. I'm pretty amazed that I still split 45 seconds on a broken leg, he added.