Luke Berry netted his 16th goal of the season as Cambridge beat Barnet 1-0 at The Hive.
The midfielder netted in the 65th minute to ensure his side, four points off the Sky Bet League Two play-off places, claimed their first win on the road in 2017.
With both senior goalkeepers out injured, Barnet handed a debut to Harry Burgoyne, on emergency loan from Wolves.
But he was untested in a first half in which neither side hit the target with John Akinde's header over the bar from Mauro Vilhete's cross the closest the Bees got.
After the break, Barnet might have gone ahead on the hour mark when Jake Carroll's back-pass was seized on by Vilhete, only for Will Norris to come racing out and block.
However, they would rue the missed opportunity when Harrison Dunk picked out Berry 12 yards from goal and the 24-year-old side-footed a volley past Burgoyne.
Barnet skipper Michael Nelson, Charlie Clough and substitute Jamal Campbell-Ryce all tested Norris late on but the Us keeper was equal to it and Cambridge hung on for a hard-fought win.