Gillingham forward Joe Gbode came off the bench to score the only goal of the game at Priestfield to put a huge dent in AFC Wimbledon's automatic promotion chances in League Two.
Gills, who are now unbeaten in seven games under Gareth Ainsworth, went in front just after the hour when Gbode produced a powerful effort from inside the box to beat goalkeeper Owen Goodman.
The visitors had created chances to go ahead themselves, the first falling to Joe Lewis, but his header from a James Tilley free-kick cleared the crossbar.
Alistair Smith also came close but his drilled effort from the edge of the box was struck wide of the left-hand post.
Those missed opportunities proved costly just after the hour when Remeao Hutton threaded through a nice for Bradley Dack.
The midfielder picked out Gbode, whose first-time effort flew into the back of the net.
Johnnie Jackson's side sent men forward in the closing stages, but the hosts defended resolutely to claim back-to-back home wins.
AFC Wimbledon remain in the play-off places with two games to play.
Match report supplied by PA Media.
