ATLANTA -- Davey Johnson didn't expect Gio Gonzalez to be this good.
Johnson and the Nationals hope Bryce Harper, only 19, keeps proving he's as good as his billing.
Harper hit his second homer in two days, Gonzalez gave up only one hit in seven innings and the NL East-leading Nationals beat the struggling Atlanta Braves 7-2 on Sunday night to complete a three-game sweep.
"It's huge," said Harper of Washington's first three-game sweep of the season, which came after the Nationals won two of three in Philadelphia.
Gonzalez (7-1) struck out 10 and outpitched Brandon Beachy (5-3) in the matchup of ERA leaders.
Gonzalez was acquired in an offseason trade after a combined 31 wins the last two seasons in Oakland.
Is this what Johnson expected of the lefty?
"No, he's better than I expected," Johnson said. "I knew he was a good pitcher. I knew he made the All-Star team with Oakland. But I thought he was a little wilder."
Harper had two hits, stretching his hitting streak to seven games. He is hitting .287 with four homers in 27 games.
"I feel really comfortable up there right now," Harper said. "I'm not trying to do too much. ... Having guys hitting around me has been huge. We've been scoring a lot of runs."
Washington's first sweep at Turner Field in three years left the Braves with a seven-game losing streak, their worst skid since dropping nine straight in 2010.
"We just haven't, as a whole, been playing like we're capable of playing," said Braves second baseman Dan Uggla, whose ninth-inning double was one of only three hits for Atlanta.
The Braves are struggling without Chipper Jones, who was placed on the 15-day disabled list with a left leg contusion on Saturday. Catcher Brian McCann has not started a game in a week due to an illness, and first baseman Freddie Freeman was held out with ongoing vision problems.
"I know we've got injuries," Uggla said. "Everybody's got injuries. You've got to battle through it."
"There are no excuses," Gonzalez said. "Look at their DL. Look at the DL of the (Cardinals) who are coming in tomorrow."
The Nationals took the lead with four runs in the sixth. They scored at least seven runs in each game of the series.
At 29-18, the Nationals moved 11 games over .500 for the first time since their 2005 inaugural season in Washington.
Beachy's 1.77 ERA, the best in the major leagues, did not change as he permitted three runs -- only one earned -- on three hits and four walks in five-plus innings. He was pulled with the game tied at 2 after hitting Danny Espinosa with a pitch to open the sixth.
The Nationals jumped on former Washington pitcher Livan Hernandez following Beachy's exit. Hernandez walked Rick Ankiel on four pitches before Jesus Flores gave Washington the lead with an RBI single. Steve Lombardozzi added a two-run double.
The losing streak is having a toll on Braves fans, who booed after the hit by Lombardozzi. There were more boos from the crowd of 38,543 after Lombardozzi scored easily from second when right fielder Jason Heyward bobbled Ryan Zimmerman's single.
Flores had three hits. He left the game following his third hit in the seventh with a mild strain of his right hamstring.
Harper hit his homer, a high shot into the right-field seats, off Hernandez in the eighth.
Atlanta added a run in the third. Bourn had a one-out triple for Atlanta's lone hit off Gonzalez and scored on Pastornicky's suicide squeeze.
Flores had a run-scoring and Gonzalez hit a sacrifice fly as the Nationals tied the game with two runs in the fourth.
Washington's only other sweep this season came in a weather-shortened series. The Nationals won two games against Miami on April 20-21 before the third game was postponed due to rain.
Braves third baseman Juan Francisco did not start after Fredi Gonzalez said he "tweaked something" on Saturday, when he had three hits. Francisco had a pinch-hit single off Stammen in the eighth.
The Nationals had been 0-9 this season when closing out a series with a sweep on the line. ... Plate umpire Kerwin Danley went down to the ground in the third inning after he was hit in the groin area when a pitch from Beachy bounced past C J.C. Boscan. Danley remained in the game following a visit from Braves assistant trainer Jim Lovell. ... The last time the Nationals were 11 games over .500 was July 25, 2005, when they were 55-44. ... The Braves will open a three-game home series against St. Louis on Monday with RHP Tommy Hanson facing RHP Lance Lynn. The Nationals open a series at Miami on Monday. RHP Jordan Zimmerman will face RHP Carlos Zambrano.