DeLeon missed with another effort, this time a shot from outside the box, just before half time and the teams went in level at the break.
The second half began in the same way as the first, with few real chances on either side. That was until the 60th minute, when Lionard Pajoy rose highest to head home a corner and give DC the lead.
It could have been two shortly after but Kyle Porter's long-range effort was tipped over by Rimando.
The away team pushed hard for an equaliser with a series of corners and free kicks as the game moved into the final stages, but failed to really test DC's goalkeeper.
United almost made it 2-0 on the counter-attack in the final minute but Carlos Ruiz's shot was saved well.
It didn't matter, though, as DC took all the points to move to the top of the conference with several other teams yet to play in this round of games.