Dany Heatley and Jason Spezza each had a goal and two assists to help Ottawa beat Washington 5-2 on Sunday.
The Senators are 7-0-1 in their last eight games against the Capitals, who controlled play in the early minutes before Ottawa took command.
"Washington came out hard today and played very forcible, aggressive and really chased the puck," Ottawa coach Bryan Murray said.
"After the first period when we got the lead, it gave us a little bit better play as the game went on. I thought we wore them down a little bit."
The Capitals had three power plays in the first 7:10 - and had a two-man advantage for 59 seconds - but couldn't score.
Ottawa, meanwhile, scored an early goal and never lost the lead. The Senators slowly began to take command during the first period.
"We knew Washington has been playing well," Ottawa's Daniel Alfredsson said. "They work hard. Coming up with a win was big for us, no question."
The Senators finished a five-game trip with a 4-1 record after also beating Toronto, Atlanta and Tampa Bay.
"Ten days on the road is a long time," said Ottawa goalie Ray Emery, who finished with 25 saves. "We wanted to bear down today. It will be nice to get back to our own beds for a few nights."
Wade Redden, Patrick Eaves and Chris Neil also scored for Ottawa as the Senators improved to 38-0 when scoring at least four goals.
Chris Clark and Jamie Heward scored for Washington.
Eaves gave Ottawa a 1-0 lead, beating goalie Olaf Kolzig off a rebound 4:54 into the game.
Washington appeared to have scored the first goal 1:25 earlier when Alex Ovechkin batted a puck out of the air into the Ottawa goal. But officials ruled Ovechkin's stick was above the crossbar and disallowed the play.
Ovechkin went scoreless for the second straight game as Ottawa defensemen Zdeno Chara and Chris Phillips shadowed him.
"What happens that in these games, unless you're getting secondary offense, it's not just (Ovechkin)," Washington coach Glen Hanlon said. "That's why you need secondary scoring and the power play."
Redden added a power-play goal with 5:55 left in the period for a 2-0 lead, breaking Ottawa's 0-for-17 extra-man drought in road games.
Clark cut the lead to one later in the period, but the Senators made it 3-1 when Spezza scored on a breakaway 7:57 into the second period. Neil scored Ottawa's second power-play goal 41 seconds into the third period for a 4-1 lead.
Heatley scored the game's final goal late in the third period.
"They're a good team" said Washington center Jeff Halpern. "Not only are they a good team, but when they're up and they play their system as well as they do...it makes for tough sledding."
Notes: Clark's goal and assist gave him 100 career points. ... Washington's last win against Ottawa came on March 28, 2003. ... Spezza has 21 multipoint games this season. ... Redden's last two goals have come against the Capitals - after he scored only two goals in his first 31 career games versus Washington.