CONCACAF Champions League Review: MLS clubs shine
DC accounted for Jamaican outfit Waterhouse 1-0, before Canadian side Montreal coughed up a two-goal lead on their way to winning 3-2 away to FAS.
In Washington, DC took the lead in the fifth minute courtesy of Eddie Johnson's finish to a well-constructed lead-up.
Defender Conor Shanosky's well-weighted ball through from well inside his own half released David Estrada.
From the right byline, Estrada pulled a cross back for Johnson, who finished high into the Waterhouse net past goalkeeper Richard McCallum.
It was all Ben Olsen's men needed to secure the three points at the Robert F Kennedy Memorial Stadium, and move top of Group Four.
In San Salvador, hosts FAS put up a spirited comeback before falling to defeat to Frank Klopas' men.
Montreal blitzed the home side early, as Andres Romero and Marco Di Vaio goals made it 2-0 inside nine minutes.
Romero was played through by number nine Di Vaio, finishing coolly with his left, before Di Vaio got on the scoresheet moments later after being laid a pass into a plethora of space inside the area by Ignacio Piatti.
FAS began their comeback in the 33rd minute, when Jorge Moran's long-range effort deflected into the Montreal net.
And Nelson Ancheta's side were level six minutes after the break when substitute Marcio Teruel, who came on after 12 minutes for Juan Granados, converted from the spot.
However, Montreal earned a penalty of their own - one Di Vaio dispatched on the hour-mark to give the visitors the lead back for good.
Montreal top Group Three, while FAS sit bottom after one match.