Miller got off to a dream start, leading the gold-medal pace by 0.31 seconds through the upper part of the course.
But he faded in the lower part of the course, and finished 8th.
Things began to go wrong for the 36-year-old when he smashed into a gate panel at 1 minute, 25 seconds into his run.
He's known for his aggressiveness, but he may have taken too tight a line here:
Cut it too close (via the BBC):
via BBC
From there he steadily lost speed, and finished well outside medal position.
"One gate and the speed was gone ... that's racing," said American skier Julia Mancuso, who was analyzing the event on Twitter.
Mattius Mayer of Austria took gold, Italy's Christof Innerhofer won silver, and Kjetil Jansrud of Norway won bronze. Aksel Lund Svindal, the heavy favorite, finished fourth. The final standings:
Miller, one of the most decorated American ski racers ever, will almost certainly finish his career with one medal in the downhill, a bronze in 2010.
He was devastated at the finish line:
Julian Finney/Getty Images