Keanu Marsh-Brown struck five minutes from time on his Barnet debut to help the Bees to an important win against AFC Wimbledon.
The Dons dominated much of the game but could not find a way through, with Chris Hussey's disallowed goal 15 minutes from time their best chance.
And the hosts were made to pay when Marsh-Brown slotted past John Sullivan late on to snatch all three points.
The result leaves both clubs just three points above the relegation zone.
Barnet, who are unbeaten in four, are now 18th while AFC Wimbledon, who have lost their last two, are one place below in 19th.