LONDON -- One moment Morgan Uceny was in the middle of the pack, getting ready to make her move in the 1,500 meters.
The next, she was down and pounding her palms on the track in frustration.
Another major meet, another major fall for the American runner.
Uceny was tripped from behind on the last lap of the final Friday night, landing hard on her right knee and hip. She was in position to challenge for a medal, but her performance goes down as "DNF" -- did not finish.
She was on her hands and knees, staring at the track in disbelief, when Asli Cakir Alptekin of Turkey won the race.
Shortly after, Uceny trudged off the track -- blood dripping from her leg -- and into the medical area. She left the stadium without speaking to reporters.
Last year at the world championships, Uceny, of Mammoth Lakes, Calif., entered the race as one of the top runners. But she became entangled just before the final lap and fell, all but ending her chances for a medal. She did pick herself up and finish a disappointing 10th.
This time, there was no getting up.
Uceny's fall was a reminder of what happened to Mary Decker Slaney, an overwhelming favorite to win gold in the 3,000 at the 1984 Olympics in Los Angeles. In one of the most memorable moments in Olympic history, Slaney collided with barefooted runner Zola Budd and tumbled to the track.
In tears, her eventual husband, British Olympic discus thrower Richard Slaney, helped her from the track.
No one was all that sure what happened to Uceny. She was comfortably cruising along before crashing to the ground. British runner Lisa Dobriskey was tucked in right behind Uceny and didn't get a good look at what took place.
"Too many bodies running together and too comfortably," Dobriskey said. "I think someone got tangled up with her. She just went flying -- with quite a big bang.
"But it wasn't me that clipped her. It was just too many bodies."