The Nationals led 9-0 after five innings, but Atlanta scored four runs in both the sixth and eighth innings and took a 10-9 lead in the top of the ninth on Michael Bourn's two-run triple.
Craig Kimbrel blew his second save in 30 chances in the bottom of the ninth when Danny Espinosa hit a solo homer into the visitors' bullpen in left-centre field to tie the game at 10.
In the top of the 11th, Dan Uggla led off with a single against Tom Gorzelanny (2-2), advanced to second on Ryan Zimmerman's throwing error and then went to third on a passed ball before scoring on Janish's bloop.
Eric O'Flaherty (2-0) pitched the 10th to earn the win, and Chad Durbin was perfect in the 11th for his first save. It was the Braves' largest comeback since 1987, and the nine-run lead was the largest ever given up by the Nationals franchise, including the games playd as the Montreal Expos.
CARDINALS 4, CUBS 1
ST. LOUIS (AP) — Kyle Lohse worked seven strong innings and the St. Louis Cardinals' slumbering offence ended Ryan Dempster's 33-inning scoreless streak with a three-run first in a victory over the Chicago Cubs.
Matt Holliday added a home run estimated at 469 feet, the longest at 7-year-old Busch Stadium, in the third inning.
Lohse (10-2) won his fourth straight decision over five starts to complement a lineup that topped three runs for the first time in 12 games. The defending World Series champions found an unlikely victim in Dempster (5-4) after totalling 15 runs and going 8 for 51 (.157) with runners scoring position on a 1-5 trip that left them five games back in the NL Central to start the day.
Dempster hadn't allowed a run since May 30 while winning five straight starts and entered with a major league-best 1.86 ERA.
GIANTS 7, PHILLIES 2
PHILADELPHIA (AP) — Brandon Crawford hit a grand slam and drove in five runs, Tim Lincecum threw seven sharp innings and the NL West-leading San Francisco Giants beat the Philadelphia Phillies.
Ryan Howard hit a solo homer for the last-place Phillies, who have lost two in a row after winning four straight.
Lincecum (4-10) looked more like the pitcher who was a two-time Cy Young Award winner than the one who entered with a 5.93 ERA. He allowed two runs and five hits, striking out six.
Phillies starter Vance Worley (5-6) gave up six runs and six hits in six innings, striking out nine.
DODGERS 7, METS 6
NEW YORK (AP) — Matt Kemp homered early and the Los Angeles Dodgers hammered a struggling Johan Santana before holding off the New York Mets.
Luis Cruz connected for his first major league home run and the Dodgers finally solved Santana (6-7), who entered 5-0 with a 0.50 ERA in five career starts against them. That included eight innings of three-hit ball in a 5-0 win June 30 at Los Angeles, but the two-time Cy Young Award winner has hit the skids hard since.
In addition to the two-run homers by Kemp and Cruz off Santana, the Dodgers got RBI singles from Jerry Hairston Jr. and Juan Rivera. The early offence benefited starter Aaron Harang (7-5), who allowed one earned run in five innings.
Kenley Jansen worked a scoreless ninth for his 17th save.
PIRATES 4, MARLINS 3
PITTSBURGH (AP) — Pedro Alvarez hit his 20th homer of the season, Andrew McCutchen had two hits to boost his batting average to a major-league best .372 and the Pittsburgh Pirates beat the Miami Marlins.
Kevin Correia (7-6) overcame a shaky start to win his fifth consecutive decision. Joel Hanrahan worked out of a two-on, one-out jam for 27th save as the Pirates moved to a season-best 12 games over .500 (52-40) and remained a half-game behind Cincinnati for first place in the NL Central.
Neil Walker led off the sixth with a homer off Ricky Nolasco (8-8) to help the Pirates rally for their 27th come-from-behind victory, second-most in baseball.
Jose Reyes had three hits, including his fifth homer of the season, for the Marlins.
REDS 3, BREWERS 1
CINCINNATI (AP) — Homer Bailey pitched eight innings for his first career win over the Milwaukee Brewers, and Zack Cozart hit the first of Cincinnati's three solo homers for a victory that kept the Reds in first place in the NL Central.
The Reds have won nine of their last 11, moving 13 games over .500 for the first time this season.
Bailey (9-6) has beaten the defending World Series champion Cardinals and the defending division champion Brewers in his last two starts. He's won four straight starts for the first time in his career. Aroldis Chapman earned his 16th save.
Cozart, Jay Bruce and Scott Rolen homered off Marco Estrada (0-4), who gave up seven hits overall in seven innings.