Braun, Brewers rally to beat Cubs, 5-2
George Kottaras homered in the fourth for the Brewers, who lead St. Louis by 9 1-2 games in the NL Central.
Barney made two mistakes in the fifth that cost Chicago, which leads the majors with 110 errors.
He failed to touch first base on a sacrifice bunt by Nyjer Morgan, then his throw over the head of third baseman Aramis Ramirez allowed Corey Hart and Braun to score.
Brewers starter Randy Wolf (11-8) allowed a leadoff homer to Starlin Castro before winning his fifth straight.
Wolf left with a man on second and two outs in the seventh for Takashi Saito, who struck out Castro to end the threat. In the bottom of the inning, Prince Fielder singled in his 101st run this season to make it 5-2.
Francisco Rodriguez pitched a quiet eighth and John Axford converted his 38th save in the ninth by getting Blake DeWitt to ground out with runners at second and third.
The Brewers improved to a majors-best 48-16 at home as they continue to show little signs of slowing down in their quest for their first division title since winning the AL East in 1982 on the way to their only World Series appearance.
Castro homered to start a game for the first time in his career and Chicago went ahead 2-0 on Jeff Baker's double in the third after an error by Wolf, but Kottaras answered with a towering solo shot in the fourth.
In the fifth, Hart singled to extend his hitting streak to nine and Morgan laid down a bunt that Cubs starter Rodrigo Lopez (4-5) fielded. Lopez's throw was just a little low and Barney, who moved from second base to cover first on the play, pulled his left foot off the bag to field it, allowing Morgan to reach.
Braun followed with his double that hit the top of the wall, but landed just below the yellow line. As Braun hustled to second, Barney took right fielder Reed Johnson's relay throw and fired over Ramirez's head into the Cubs dugout.
Third base umpire James Hoye awarded both Hart and Braun home to give Milwaukee a 4-2 lead.
Wolf has been another important reason why the Brewers' rotation has been so strong. The veteran left-hander who turned 35 on Monday has won five in a row for the first time since pitching for the Dodgers in 2009. He went 6 2-3 innings, allowing one earned run on four hits to lower his ERA to 3.37.
NOTES: The Cubs have lost six straight in Milwaukee. ... Wolf's career-best ERA was 3.20 with the Phillies in 2002. ... It was Kottaras' first home run since June 18. ... Ramirez doubled in the first to extend his hitting streak to 15 games. ... Saturday's matchup features Brewers RHP Yovani Gallardo (14-8, 3.51 ERA) against Cubs RHP Ryan Dempster (10-9, 4.60).