Against Sri Lanka, Akbar Ali smashed 32 off just nine balls to help Bangladesh post 75 in six overs.
Mosaddek Hossain then delivered with the ball, picking up 3 for 20 and earning the Player of the Match award, as Sri Lanka were held to 61 in response.
Earlier, their fixture against hosts Hong Kong was washed out due to rain.
With the win, Bangladesh set up a quarterfinal clash against Australia on Saturday.
