Starter Brad Bergesen didn't last beyond the fourth inning, but the Orioles' bullpen cushioned his fall.
Four relievers combined for five scoreless innings, holding the Nationals to one hit and one walk, with two strikeouts.
Major props to Mark Hendrickson, Jason Berken, Will Ohman and Alfredo Simon.
Hendrickson gave up the only hit in his two innings. Berken issued the only walk over 1 1/3 innings and earned his first victory.
"He's doing a tremendous job for us coming in late," interim manager Juan Samuel said of Berken. "You throw him out there and you know what you're getting from him. It's very comfortable for me to see him."
Simon picked up his eighth save with a routine ninth inning, getting a fly ball, strikeout and grounder.
Samuel let his club pass the baton a little too much for my comfort, but nobody cares about my comfort. It worked out just fine.