Falkirk 1-2 Dumbarton
Dumbarton struck twice in the first half to overcome Falkirk, who were reduced to 10 men in stoppage time.
Garry Fleming turned Jordan Kirkpatrick's low drive past a helpless Michael McGovern.
Mitchel Megginson then met Paul McGinn's cross with a well-placed right-footed effort.
A stunning strike from Philip Roberts reduced the deficit six minutes before the break, but the forward picked up a late second yellow card.
It blotted his copybook after his goal, butting in from the left-hand side before unleashing a long-range effort that flew past Jamie Ewings into the top-left corner.
Falkirk had a strong appeal for a penalty turned down 10 minutes into the second half when Chris Turner brought Blair Alston down in the box.
Alston almost punished the Sons again two minutes later, letting fly with a right-footed effort that rattled off the crossbar.