The Nationals also have a chance at their first home sweep of the Braves in more than five years in Wednesday night's series finale.
With Monday's series opener postponed after the Navy Yard shootings, Washington took both games of a day-night doubleheader Tuesday, 6-5 and 4-0. The Braves (89-62) could have clinched their first NL East title since 2005 with victories in both, but instead the club's magic number remains at four. They'll have to wait until Friday at the earliest to wrap up the division.
Atlanta closer Craig Kimbrel's string of 37 consecutive converted saves was snapped in the first game as Andrelton Simmons' error lead to the go-ahead run in the bottom of the ninth.
Rookie Tanner Roark held the Braves to just two hits over seven innings in the second contest while Denard Span collected a single in each game, extending his hitting streak to 28 contests, the longest in the majors this season. He's hitting .378 during the streak with 19 runs scored.
Washington (81-70), which has won 10 of 11, trails Cincinnati by 4 1/2 games for the NL's second wild-card spot, while Atlanta still holds the NL's best record despite dropping nine of 13.
"I like where we are, our position, but there's still baseball games to be played," Braves manager Fredi Gonzalez said. "We've just got to get back on a roll again."
The Nationals entered the series 4-12 versus Atlanta this year, but now have a chance at their first home sweep of the Braves since Aug. 29-31, 2008.
Trying to clinch that sweep will be Ross Ohlendorf (4-0, 3.15 ERA), who filled in Friday against Philadelphia after Stephen Strasburg was scratched. The right-hander gave up a run on two singles and a walk in the first inning, but recovered nicely, allowing three more hits and another walk over four additional scoreless innings in a 6-1 win.
"He made the pitches," manager Davey Johnson said. "Great effort."
Ohlendorf gave up six runs in 3 2-3 innings the last time he matched up with the Braves, a 7-0 loss for Pittsburgh on May 21, 2010.
Atlanta will counter with rookie left-hander Alex Wood (3-3, 3.45), who had his scheduled start Thursday versus Miami skipped in order to give him more rest. That decision came on the heels of two rough starts as he gave up a combined 11 runs over seven innings. He didn't record a decision after yielding four runs and a season-high nine hits over 4 2-3 innings of a 6-5 loss at Philadelphia on Sept. 7.
"It's very frustrating," Wood said. "I'm trying to help my team clinch a pennant. I'm not doing exactly what I want to do when I go out there."
Perhaps facing Washington could get him back on track as he limited the Nationals to one run and five hits over 6 1-3 innings of a 3-2 victory on Aug. 16 with a season-high nine strikeouts.
Freddie Freeman became the first Brave to reach the 100-RBI mark since Chipper Jones and Jeff Francoeur in 2007 by driving in his 100th on Tuesday afternoon. He's hitting .352 over his last 28 games versus Washington with 23 RBIs.