Updated

Tanner Roark pitched seven shutout innings and Ryan Zimmerman hit a solo home run as the Washington Nationals took a 4-0 win over the Atlanta Braves to sweep Tuesday's doubleheader.

Roark (7-0) won his third straight start as he gave up just two hits and a walk while striking out six. Ian Desmond, Adam LaRoche and Steve Lombardozzi each drove in a run in the win.

"What a great game from Roark," said Washington manager Davey Johnson. "He was completely in command the entire time he was up there. His pitch count got kind of high there, so that's why I took him out. He earned that win today."

Having won three straight and nine of their last 10, the Nationals are 4 1/2 games back of the Reds for the final wild card spot in the National League. Cincinnati defeated Houston on Tuesday.

Atlanta, meanwhile, is still stuck at a magic number of four to clinch its first NL East title since 2005 as the team has lost three straight and five of its last seven.

"I like where we are at and our position, but there's still baseball games to be played," said Atlanta manager Fredi Gonzalez. "We've just got to get back on a roll again."

Freddy Garcia (1-2) gave up one run on seven hits with a pair of walks and six strikeouts over seven innings to take the loss.

In the earlier game, the Nationals scored three runs in the ninth inning to take a 6-5 victory.

The doubleheader was played on Tuesday due to Monday's game being canceled in the wake of a deadly shooting at the Washington Navy Yard. The Navy Yard is just blocks away from Nationals Park.

Washington plated a run in the second as Bryce Harper led off with a single, stole second and later scored on a Lombardozzi single for a 1-0 lead.

Both of Atlanta's hits off Roark came in the second inning as Gerald Laird hit a two-out single and Dan Uggla followed with a base hit. Andrelton Simmons, though, hit into a fielder's choice to end the frame.

After walking Jordan Schafer with one out in the third, Roark retired the next 14 batters he faced before the bullpen took over.

Zimmerman hit his solo homer in the eighth, while Desmond doubled in a run and LaRoche followed with an RBI single for a 4-0 lead.

Game Notes

Despite the two losses today, Atlanta still leads the season series, 12-6 ... Atlanta batted 0-for-4 with runners in scoring position and stranded six ... Game Time: 2:25.