Curtis Granderson and Robinson Cano homered for the Bombers as they completed a three-game series sweep of Washington, stamping an exclamation point on a successful Interleague road trip.
"We're a home run-hitting club, there's no doubt about it," Yankees manager Joe Girardi said. "That's how we're going to score most of our runs. We won a game today hitting home runs."
Rafael Soriano pitched a scoreless ninth for his 13th save as the Yankees swept their third straight three-game series, having run through the Mets and Braves last week.
New York hadn't swept three straight series of three games or more since wiping through the Phillies, Orioles and Rays from June 30-July 12, 1998, on their way to a franchise-record 114 wins and a World Series crown.
"I've said it dozens of times -- no one in here panics, no one in here gets too down," Yankees first baseman Mark Teixeira said. "And you're not going to see us dancing on the tables now. We've got a lot of season to go, a lot more wins that we need, and we're going to keep trying to play good baseball."
Nova allowed just Adam LaRoche's second-inning home run over 7 2/3 innings as he scattered seven hits, walking one and striking out four in his first career start against the club.
"I think [it's] the work that I've been putting in, the focus," Nova said. "I've been working really, really hard to especially get my ground balls back, and today I made really good pitches. I got ground balls when I needed it."
Nova became just the fourth pitcher in the Majors to reach nine victories, following the Mets' R.A. Dickey (10), the Cardinals' Lance Lynn (10) and the Phillies' Cole Hamels (9). He walked off to a standing ovation from the pro-Yankees contingent of a sellout crowd of 41,442.
"He pitched well last year and he's just carried it over," Yankees captain Derek Jeter said. "He always has a lot of confidence. He threw strikes today. He's been pretty much doing this for a year and a half."
The Yankees managed two runs in six innings off Nationals starter Edwin Jackson, though in the continuation of a season-long issue, they also finished 0-for-12 with runners in scoring position.
"We're still not happy about that," Teixeira said. "I wish I could tell you the issue. I don't know, I really don't. We just have to be better with runners in scoring position. But our pitchers have picked us up; our pitchers have picked us up all year. If it's not for them being so good, we're not in first place right now."
Teixeira brought home New York's first run with a bases-loaded sacrifice fly to center field in the first inning, and Granderson unloaded on his team-leading 21st home run facing Jackson in the fifth.
"You feel like your guys are going to get it done when you're playing as well as we are," Girardi said. "No matter what the situation is, you feel like you're going to get it done."
The Yankees added two runs in the seventh inning against reliever Tom Gorzelanny, who took over after Jackson completed his seven-hit, three-walk workload, posting one strikeout.
Cano slugged his 12th home run of the season, a solo shot to left-center, and Teixeira doubled before scoring on a passed ball with the fourth Yankees run.
"The one guy we kept pretty quiet the whole series -- of course, I walked him about any time I had a chance -- was Cano," Nationals manager Davey Johnson said. "I didn't want to let that second baseman beat us. But there's plenty of a cast of characters around him that can pick up the slack. They've got a good ballclub. They're going to be tough to catch."
Of course, that won't be the Nats' problem; they're done with the Yankees for the rest of their schedule and happy to leave that challenging task to the AL East as 2012 drives forward.
"It starts with our pitching," Jeter said. "Our starters have been great. Our bullpen has been outstanding. Even when we haven't scored a lot of runs, they've kept us in the games. We've been playing good for quite a while now."