MILWAUKEE -- It was Mike Leake's roughest outing of the season, but considering the body of work he has put forth so far, that is not saying much.

Leake (3-1) allowed just two runs -- a season high -- on three hits while striking out six over six innings as the St. Louis Cardinals wrapped up another series victory by knocking off the Milwaukee Brewers 6-4 Sunday afternoon at Miller Park.

"I thought he pulled it together when he needed to," Cardinals manager Mike Matheny said. "Those lead walks kind of atypical from what we've seen, free bases at all, really, with what he's done and how well he's controlled the strike zone. Those hurt you a couple times, especially if you've got guys that can run like they have.

"He did a nice job in the first with keeping it to just the one run and pitching out of trouble. He got himself out again later on. I thought once he settled in, it seemed like it was the same guy that we'd seen all season."

Leake began the day leading the National League with an 0.84 ERA but found himself in trouble early, putting a pair on with one out in the first. From there, though, it was fairly smooth sailing for the veteran right-hander, despite allowing three leadoff walks.

"It was just one of those days, not being able to completely pinpoint where I wanted it," Leake said. "But I was able to at least get what I needed done and get a win."

Brewers right-hander Jimmy Nelson (1-1) battled with his command and walked a season-high six batters while striking out five and allowing five hits in 5 1/3 innings of work.

"Walks are always frustrating," Nelson said. "I went through a stretch there where I lost some (velocity).

"You just try to calm down, slow down and not try to do too much. (Catcher) Manny (Pina) did a good job of slowing me down. I battled to get out of it, tried to minimize the damage and give our guys a chance."

After Nelson struck out a pair in the first, the Brewers gave him a lead in the bottom of the inning, going up 1-0 on an RBI double from Ryan Braun.

Catcher Manny Pina erased a leadoff walk in the third from Kolten Wong by picking him off at second base, but an error on Travis Shaw allowed Leake to reach base. After a walk to Dexter Fowler, Leake scored on an Aledmys Diaz base hit to even the score at 1.

Shaw atoned for his mistake with a sacrifice fly in the bottom of the inning, putting the Brewers back in front, but walks to Stephen Piscotty and Randal Grichuk to open the fourth led to a three-run inning for the Cardinals.

Eric Fryer, starting in place of Yadier Molina, and pinch hitter Matt Adams drove in insurance runs with back-to-back two-out singles off right-hander Jared Hughes in the eighth.

Matheny wanted to rest closer Heung Hwan Oh, who had worked each of the last two games. But after right-hander Jonathan Broxton allowed a leadoff home run in the ninth to Pina and Keon Broxton reached on an error, Matheny turned to Oh, who walked pinch hitter Hernan Perez. After striking out Domingo Santana, Oh gave up an RBI single to Jonathan Villar.

Oh struck out Eric Thames and got Braun to fly out, clinching his fifth save of the season.

"It was a good rally," Brewers manager Craig Counsell said. "Manny started off with a heck of an at-bat. Keon's at-bats throughout the series have significantly improved. He's taking another step in the right direction for sure. HP had a nice at-bat. We put together some nice at-bats. We had the guys up there at the end that we certainly wanted, but it just didn't work."

NOTES: Milwaukee's Eric Thames made his third outfield start of the season Sunday, manning right field, as manager Craig Counsell gave Jesus Aguilar a start at 1B, his sixth of the year. Aguilar opened the season batting .636 but has gone 1-for-15 since the hot start. ... Brewers 2B Jonathan Villar got off to a slow start this season but brought a four-game hitting streak into the contest Sunday. ... With a scheduled off day on Monday, St. Louis manager Mike Matheny kept C Yadier Molina out of his starting lineup against the Brewers. Molina has started in 16 of the Cardinals' 19 games this season.