Gold medal winner Gabrielle Douglas of the US performs on the asymmetric bars. REUTERS/Mike Blake
Komova was reduced to tears for the second time in three days when Douglas pipped her to the title by 0.259 of a point after producing the day's best performances on the vault and the beam.
Aliya Mustafina, who with Komova took team silver behind the Americans on Tuesday, clung on for bronze despite a fall from the beam.
She and Douglas's compatriot Aly Raisman finished with the same total but the Russian won the medal on the tiebreak rule.
Douglas, dubbed the "Flying Squirrel" for the shape she produces on the bars, was watched from the stands by team mate and world champion Jordyn Wieber, who had come into the Games touted as the favourite but failed to qualify for the final.
