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WASHINGTON -- The New York Yankees are used to big crowds, used to so-called "playoff atmospheres" in the regular season. The clubhouse is stocked with players who know what it's like to be in first place.

Those are relatively new sensations for the on-the-rise Washington Nationals, who received a lesson or two in the Yankees' first trip to the nation's capital in six years. New York swept the series between division leaders, capping the three-game set Sunday with another solid performance from starter Ivan Nova in a 4-1 win.

"When you're playing as well as we are, no matter what the situation is, you feel like you're going to get it done," Yankees manager Joe Girardi said.

Both teams entered the series riding six-game winning streaks. The Yankees are now up to nine, their longest since May 2009. The series drew the eighth, ninth and 10th largest crowds in the 4½-year history of Nationals Park, with fans in pinstripes trying to outshout the locals in red.

"I think that's the one good thing that came this weekend," said first baseman Adam LaRoche, whose second-inning homer accounted for Washington's lone run Sunday. "That's about as close to a playoff atmosphere as you're going to get. ... You get the place packed, people going crazy and obviously it draws a lot of media attention. It'll be good for these guys, especially the young guys, to get used to that."

Nova (9-2) gave up seven hits and a run in an efficient, mostly trouble-free 7 2/3 innings to win his fifth straight start. He is also unbeaten in his last 15 road starts -- a streak that's been going for more than a year. He is 12-0 away from Yankee Stadium since losing to the Los Angeles Angels in Anaheim on June 3, 2011.

The offense, as usual, came from the long ball. Curtis Granderson and Robinson Cano hit the 98th and 99th Yankees homers of the season -- both solo shots -- to make up for another abysmal day (0 for 12) with runners in scoring position. New York is hitting a mere .216 with men on second and third this season.

"We're still not happy about that," said Mark Teixeira, who went 3 for 4 with a pair of doubles and drove in a run with a sacrifice fly. "I wish I could tell you the issue. We just have to be better at hitting with runners in scoring position. We can talk about offense all we want; the fact is our pitching staff is why we are here today."

Granderson homered off Edwin Jackson (3-4) in the fifth to break a 1-1 tie. Cano made it a two-run cushion in the seventh off Tom Gorzelanny. Another run came in the seventh on a passed ball by Nationals catcher Jhonatan Solano, who had another passed ball later in the inning.

Nova was pulled with two outs and a runner on base in the eighth. Boone Logan finished the inning, and Rafael Soriano pitched a perfect ninth for his 13th save.

The Yankees maintained a 1½ game lead over the Baltimore Orioles in the AL East. The Nationals also remain in first -- four games clear of the Atlanta Braves in the NL East -- but they hit a buzz saw, getting swept at home for the first time this season and scoring only six runs in the three games.

"We've got to play better than that," Washington third baseman Ryan Zimmerman said, "if we want to beat teams like that."

In particular, Zimmerman needs to hit better. He went 0 for 4 Sunday and 1 for 13 in the series to drop his average to .229.

"What really concerns me is we've got to get Zim going," Washington manager Davey Johnson said. "We've got to get Zim to a happy place."

Game notes

The Yankees have swept three consecutive series of three games or more for the first time since 1998. ... The sweep leaves the Cincinnati Reds (7-5) as the only major league team with an all-time winning record against the Yankees. ... Washington's 19-year-old Bryce Harper, who went 0 for 7 with five strikeouts in Saturday's 14-inning loss, rebounded with a double and a single. ... Washington SS Ian Desmond booted a grounder in the fourth, giving him an error in each game of the series. ... Yankees OF Nick Swisher sat out with a bruised quad sustained on a slide into home in Saturday's game. He was limping badly in the clubhouse after Sunday's game. ... The Nationals designated struggling reliever Brad Lidge for assignment. Lidge, 35, went 0-1 with two saves and a 9.64 ERA in 11 appearances and gave up five runs in the first two games of the Yankees series. ... Ryan Mattheus, activated to take Lidge's roster spot, pitched 1/3 inning Sunday.