ATLANTA -- Andrew McCutchen homered for Pittsburgh's only runs, and the Pirates stumbled in their chase for the NL Central title, falling to the Atlanta Braves 6-2 on Wednesday night.
The Pirates, who clinched a playoff spot on Tuesday night, began the night 1 1/2 games behind St. Louis. Pittsburgh lost for only the fourth time in its last 19 games.
McCutchen had two hits, including a two-run homer in the fifth inning after Atlanta led 6-0.
Jeff Locke (7-6) allowed six runs and 13 baserunners - eight hits and five walks - in only four innings.
Justin Upton hit a two-run homer and pitcher Julio Teheran and Emilio Bonifacio each had two-run singles as Atlanta ended a five-game losing streak. Teheran (14-13) allowed six hits and two runs in five innings.
The loss also brought an injury concern for the Pirates. Catcher Russell Martin left the game in the fifth inning with tightness in his left hamstring.
The Braves improved their dismal September record to 5-16. Their six runs matched their combined output in the five straight losses.
Pittsburgh lost a day after its clubhouse celebration at Turner Field, where champagne and beer flowed freely. The Pirates wrapped up their postseason berth exactly one year after clinching a place in the 2013 playoffs to end a 21-year drought.
McCutchen drove in Starling Marte, who had two hits, with his 25th homer.
Josh Harrison's ninth-inning single off Jordan Walden gave him a 12-game hitting streak. Marte followed with a sharp grounder which third baseman Phil Gosselin bobbled for an error, putting runners on first and second with one out.
Upton set a career high with his 28th homer. He has 99 RBIs, also a career high.
Christian Bethancourt hit two ground-rule doubles for Atlanta.
Pirates: Martin singled in the second inning and seemed to hurt himself when he returned to first base on a pickoff throw. He remained on one knee for several seconds before rising slowly.
Braves: 3B Chris Johnson had two hits and scored two runs before he left the game in the sixth with a lower back strain. ... C Evan Gattis is expected to make his first start since Sept. 7 on Thursday night but likely won't play the full game. He has been held out with strep throat and a kidney stone.
Pirates: Edinson Volquez (12-7) will start on Thursday night in the final game of the four-game series. He hasn't faced the Braves this season and is 2-3 against Atlanta in six career starts.
Braves: RHP David Hale, replacing Mike Minor in the rotation, will make his first start since June 28 in the Braves' final home game of the season. Hale (4-4) has pitched in relief in 39 of his 44 games.