MILWAUKEE (AP) -- The Milwaukee Brewers keep winning at home, even if they're stumped over the reasons why they've been suddenly so good at Miller Park.
Nyjer Morgan hit a go-ahead, three-run double to cap a five-run fifth inning off Cardinals ace Chris Carpenter and the Brewers rallied for a 6-2 win over St. Louis on Monday night and extend their season-best winning streak to seven.
The Brewers own the best home record in the majors at 40-14 after going 40-41 at Miller Park last year.
"We feel like we have that extra confidence here, but for whatever reason the fans get so behind us and we feel like we're never out of anything," Brewers right fielder Corey Hart said. "We always knew this was going to be a big series ... Winning the first one is huge. It gives us a little momentum going forward."
Milwaukee only had one hit off Carpenter before the fifth, when the first six batters reached, including Morgan's decisive double.
""Everything worked out," Brewers manager Ron Roenicke said. "You can't explain why things fell apart, basically, for them and go well for us."
Milwaukee's timely hitting helped the Brewers (61-49) move 3 1-2 games ahead of St. Louis in the NL Central, their biggest lead of the season. The Brewers and Cardinals will play 11 more times this year.
Zack Greinke (9-4) allowed a first-inning, two-run homer to Matt Holliday , but the Brewers offense prevailed again in the second matchup this season of the former Cy Young winners after Carpenter (6-8) appeared in complete control riding a five-game winning streak.
Yuniesky Betancourt singled to lead off the fifth and Casey McGehee executed a hit-and-run single past second baseman Skip Schumaker to put runners at the corners.
Jonathan Lucroy 's chopper went over the head of third baseman David Freese to score a run and the Cardinals' defense failed to cover first or third when Greinke laid down a bunt that loaded the bases.
Hart followed with an RBI single that tied it at 2 before Morgan hit his bases-clearing double to put Milwaukee up 5-2. The Brewers tacked on a run in the seventh on Ryan Braun 's double off Mitchell Boggs .
"We find ways to scrap," Hart said. "Whether it's Prince or Yuni or Casey, it's nice to have different guys getting up there for guys."
Cardinals manager Tony La Russa said it was tough to see Carpenter (6-8) get knocked around without a ball driven well.
"It was a mess," La Russa said. "They got five runs off not enough contact. Some of that, we could have defended better. Some of it was tough breaks."
It was the first time Carpenter had given up five earned runs since he lost to Greinke, the 2009 AL Cy Young winner, on June 11. Milwaukee is 4-0 against St. Louis at Miller Park this season and Greinke is 7-0 at home.
"I know when we come home we're going to play well," Roenicke said. "I still can't tell you what the reasons are. It's a feeling that the guys have when they're home, they know they're going to play well and it goes a long way."
New acquisition Rafael Furcal singled to lead off the game for St. Louis and Holliday hit a two-out homer, his first since participating in the Home Run Derby during the All-Star break.
St. Louis loaded the bases in the fifth with one out after Greinke walked Holliday and allowed hits to Lance Berkman and Freese, but Schumaker grounded into an inning-ending double play.
"I couldn't believe that they turned it," Greinke said. "That was real nice."
Schumaker didn't think so.
"I was safe. That was a huge play," Schumaker said. "It is upsetting because it is a big play in the game."
Greinke extended Milwaukee's streak of strong starting pitching by going six innings and striking out five. The Brewers rotation has allowed three runs or less in 17 straight starts dating to the second game after the All-Star break.
St. Louis (57-52) was in a virtual tie atop the NL Central with Milwaukee and Pittsburgh on July 24, but the Brewers' winning streak has helped them open up a lead after St. Louis stumbled to a 4-3 mark in a homestand against the Astros and Cubs before heading on this seven-game road trip.
"It was the classic matchup," Schumaker said. "Greinke had great stuff going and Carp had great stuff going. It is just too bad they won and we didn't."
NOTES: Hart has three straight multi-hit games. ... Milwaukee sold out its fourth consecutive game and has 18 sellouts this season. ... The Brewers have won 11 of their last 12 at home. ... Milwaukee is 12 games above .500 for the first time since winning the NL wild card in 2008 when the Brewers finished 90-72. ... Brewers INF Craig Counsell popped out as a pinch-hitter in the sixth to extend his franchise-long hitless streak to 45 at-bats.