With Samardzija allowing just one run in seven innings and Carlos Marmol managing to escape the latest mess he created, the Cubs didn't need anything more than the back-to-back home runs from Bryan LaHair and Ian Stewart in the bottom of the fourth inning.
Hanson had surrendered just two home runs in his six previous starts this year.
"I thought Tommy pitched great, other than the two mistakes," Braves third baseman Chipper Jones said. "He was on top of everything. He was throwing all of his pitches for strikes."
Hanson allowed just two runs on five hits in six innings. Considering he had allowed four runs in just 3 2/3 innings against the Phillies on Wednesday, this was an encouraging step in the right direction.
But with his fastball still consistently sitting around 89-90 mph and only maxing out at 92 mph in the first two innings, the 25-year-old hurler still lacks the dominant form after he arrived on the Major League scene as the game's top pitching prospect midway through the 2009 season.
Still, Hanson has displayed definite determination while posting a 3.63 ERA this year without his best stuff.
"I'm getting more comfortable with all of my pitches," Hanson said. "So hopefully, I can keep on that path."
Five days after erasing a six-run deficit Hanson had helped create in his matchup against the Phillies and Roy Halladay, the Braves were unable to extend their recent offensive surge. They totaled 44 runs and 64 hits over their previous five games.
But Jason Heyward's two-out second-inning home run accounted for Atlanta's only run in the opener. Heyward homered on the first swing of his career against the Cubs at Turner Field and now has four home runs in 26 career at-bats at Wrigley Field.
"Samardzija was really, really good," Jones said. "I had only faced him out of the bullpen, but he's got some staying power. Command has always been kind of shaky for him. It looks like he's got the command thing down or at least he did tonight. He was really tough."
Facing the former Notre Dame wide receiver for the first time as a starting pitcher, the Braves quickly learned why the Cubs were wise to move him to the starting rotation. He is now 4-1 with a 3.03 ERA in through his first seven starts.
"You've got to work against that lineup as a righty pitcher," Samardzija said. "They throw some big lefty bats against you. You've got to make your pitches, you have to be on your spot with your fastball and then mix in your pitches. You're looking at [Freddie] Freeman, [Brian] McCann, Chipper, Heyward -- they're some big bats there, so you have to be careful and make your pitches."
The Braves produced at least one baserunner in five of the first six innings. But their best scoring threat against Samardzija came after he hit Heyward with a pitch and then surrendered a one-out single to Tyler Pastornicky. That attempted rally ended when Eric Hinske lined out to LaHair, who threw to Starlin Castro at second base to complete the inning-ending double play.
Rookie umpire Chris Conroy issued warnings to both benches when Braves left-handed reliever Eric O'Flaherty hit David DeJesus with a pitch with two outs in the bottom half of the seventh inning.
Braves manager Fredi Gonzalez was then ejected after coming out to the field to argue the issuing of warnings. Moments later, Tony Campana recorded a bunt single, and Castro followed with an RBI single that gave the Cubs a 3-1 lead.
After Marmol issued two consecutive walks to open the eighth, he went through the middle of the Braves' lineup without any further problems. The Cubs added a pair of run in the bottom half of the inning with Geovany Soto's two-run home run off Chad Durbin.
"We were in the ballgame," Heyward said. "That's all you can ask for from your starting pitcher."