CHICAGO — As Tommy Hanson has progressed through the season’s first month, he has not displayed the dominant form that many expected when he came to the Major League level as the game’s top pitching prospect three years ago.

Instead, the determined Hanson has attempted to persevere with the intense determination he carries to the mound for each start.

Unfortunately, Hanson’s competitive spirit did not prove to enough as Jeff Samardzija cooled a red-hot Braves offense and helped the Cubs take a 5-1 win at Wrigley Field on Monday night.

Looking to bounce back from his worst start of the season, Hanson was instead doomed by the consecutive mistakes he made in the fourth inning. The back-to-back home runs he surrendered to Bryan LaHair and Ian Stewart proved to be enough for the Cubs to snap the Braves’ three-game winning streak.

Atlanta had totaled 44 runs and 64 hits over its previous five games. But this surging bunch struggled in the club’s first opportunity to face Samardzija as a starting pitcher. The former Notre Dame wide receiver allowed one run on five hits in seven innings.

Jason Heyward accounted for that one run and extended his success at Wrigley Field with his two-out home run that sailed over the right-center-field wall in the second inning. The 22-year-old outfielder has totaled four home runs in 25 career at-bats at Wrigley Field.

Heyward was unable to add to that total when Samardzija hit him with a first-pitch fastball in the seventh inning. Home-plate umpire Chris Conroy issued warnings when Braves left-handed reliever Eric O’Flaherty hit David DeJesus with a pitch with two outs in the bottom half of the seventh.

Braves manager Fredi Gonzalez was ejected after coming out to the field to argue the issuing of warnings. Shortly after he exited the dugout, Tony Campana and Starlin Castro provided the Cubs with an insurance run on consecutive singles against O’Flaherty.

Hanson did not prove to be as fortunate as he was five days ago when the Braves erased a six-run deficit he created before exiting after just 3 2-3 innings in a matchup against Phillies ace Roy Halladay. He proved perfect in the first inning and then pitched around a walk and a hit batsman in the second inning Monday.

But after battling through a 24-pitch third inning, Hanson opened the bottom of the fourth by allowing back-to-back home runs to LaHair and Stewart. Within a span of three pitches, the 25-year-old hurler had allowed as many home runs as he had during his previous six starts this season.

Samardzija was staring at potential trouble when Tyler Pastornicky’s one-out seventh-inning single gave the Braves runners at first and second. But pinch-hitter Eric Hinske’s sharp liner was caught by LaHair, who threw to Castro at second base to complete the inning-ending double play.

The Braves were unable to take advantage of the two eighth-inning walks issued by Carlos Marmol. The erratic former closer escaped trouble by retiring Freddie Freeman, Brian McCann and Dan Uggla in order.

Notes: Cubs RHP Matt Garza, slowed by a flu bug that has hit several players, is scheduled to return to the rotation Friday in Milwaukee. He was scratched from his start Sunday. ... Heyward entered the game with a career .342 average against the Cubs and now has five homers against them. ... Braves CF Michael Bourn made two nice running catches, going over his shoulder to grab LaHair’s drive in the second and racing to left center to rob Soto of extra bases in the third. He also extended his hitting streak to 11 games with an infield hit to short in the third. ... The Cubs hit back-to-back homers for the first time since last August when Aramis Ramirez and Carlos Pena — neither of whom is still with the team — connected against Washington. ... LaHair has now reached base in 25 straight games. ... Game-time temperature was 56 and a light fog began rolling in during the late innings.