Joe Wollacott made the crucial save in a penalty shootout to send Charlton through 5-3 against QPR following a 1-1 draw.
The goalkeeper kept out the first spot-kick by Stefan Johansen.
Miles Leaburn created the first chance for the hosts after 10 minutes when he headed over a Sean Clare cross, while Niko Hamalainen blasted over the crossbar for QPR a minute later.
Charlton were on the front foot more in the second half. However, the first effort after the break fell to QPR as a low shot by Hamalainen forced Wollacott to clear.
Both teams made a number of changes on the hour but neither side showed enough quality until substitute Tyler Roberts marked his QPR debut in fine style.
The on-loan striker from Leeds rifled home a superb strike from the edge of the area with 10 minutes left.
There was late drama, however, as Aaron Henry drilled home just before stoppage time to send the tie to penalties.
