The loss drops Atlanta to 45-46 on the season, while the Cubs gain a game in the National League Wild Card race and improve to 47-45.
Although shaky at times, Julio Teheran picked up his 13th quality start of the season and his fourth quality start at SunTrust Park. He allowed two earned runs on five hits and struck out five batters while issuing four walks over six innings pitched.
Unfortunately for him, Chicago left-hander Jon Lester was lights out for the Cubs on Monday. He finished with a final line of 7 IP, 3 H, 1 R, 1 BB, 6 K and lowered his ERA from 4.25 to 4.07.
With one out in the bottom of the ninth inning, the Braves applied pressure against closer Wade Davis as Brandon Phillips and Freddie Freeman strung together consecutive singles to put runners on the corners. A wild pitch from Davis allowed Phillips to score from third and cut Atlanta's deficit to 4-2.
Matt Kemp followed suit with a single to left, scoring Freeman and pulling the Braves within 4-3.
After Tyler Flowers flew out to deep center field for the second out, Davis issued a pair of walks to load the bases for Johan Camargo. Camargo worked a 2-2 count through five pitches, but flew out to shallow left field to end the game and strand the bases loaded.
Teheran singled to center field with one out in the bottom of the third inning for Atlanta's second hit of the game. Ender Inciarte then grounded into a would-be double play, but reached and advanced to second base on a throwing error from Baez. With two outs away, Phillips singled to center field to score Inciarte and give the Braves a 1-0 lead.
Jason Heyward drew a leadoff walk in the top of the fifth inning followed immediately by a Baez single to center field to put runners on first and second with nobody out for Teheran. After a wild pitch in the ensuing at-bat advanced runners to second and third, Ben Zobrist notched a one-out ground-ball single up the middle to drive in a pair of runs and put the Cubs up 2-1.
After inducing a groundout from Kris Bryant, Teheran issued back-to-back walks to Anthony Rizzo and Willson Contreras to load the bases with two outs for Kyle Schwarber. He managed to get out of the inning with minimal damage, however, thanks to an astounding diving grab from Freeman at first base for the third out.
Ian Happ led off the top of the sixth with a double to center field and later advanced to third on a failed pickoff attempt from Teheran during Heyward's at-bat. After recording a pair of outs, Teheran issued a four-pitch walk to Jon Lester to put runners on the corners.
Lester later stole second, but no runs crossed the plate as Freeman bailed the Braves out once again with yet another spectacular diving stop at first base to escape the inning unscathed.
With one out in the top of seventh inning, Rizzo connected on a 93.1 MPH four-seam fastball low and in from reliever Ian Krol and drove it to straightaway center field for a solo home run, extending Chicago's lead to 3-1.
The Cubs added an insurance run in the eighth inning as Javier Baez hit a two-out double to left field and trotted home on a double from Addison Russell off Akeel Morris, giving the Cubs a 4-1 advantage.
Rookie left-handed pitcher Sean Newcomb (4.26 ERA, 3.49 FIP) will be on the mound for Atlanta Tuesday as he squares off against John Lackey (5.20 ERA, 5.66 FIP) and the Cubs at 7:35 p.m. ET.