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ST. LOUIS -- The leadoff spot is to Matt Carpenter as a security blanket was to Linus.

The St. Louis Cardinals first baseman, who was moved to the third spot in the lineup at the start of the year with the addition of center fielder Dexter Fowler via free agency, should have been a good fit for the new placement. With his power and patience, Carpenter is capable of 25 homers and 100 walks.

However, Carpenter is also capable of hitting for a good average, and for whatever reason, that average had slipped as low as .210 last week when manager Mike Matheny decided to make a change.

Back to the leadoff spot went Carpenter, with Fowler going to the No. 2 position. Whether it was the return to familiar grounds or the arrival of the Philadelphia Phillies over the weekend, Carpenter and Fowler started producing at the levels expected of them ahead of a four-game series against the Milwaukee Brewers that begins Tuesday with a day-night doubleheader at Busch Stadium.

In four games with Carpenter leading off and Fowler hitting second, the duo is 10-for-30 with two homers and seven RBIs. It was not a coincidence that St. Louis swept Philadelphia and averaged 5.3 runs per game.

"For whatever reason, certain guys like to hit in certain spots," St. Louis manager Mike Matheny said. "I don't care where guys are as long as guys are on base. We're just trying to find that good rhythm.

"Opposing teams see that top of the order rolling around, and that's kind of what we envisioned as this season began."

Carpenter was 4-for-12 against the Phillies with a two-run double. Fowler was 4-for-10, scoring in each game and belting a three-run homer that erased a 2-0 deficit Sunday in St. Louis' 6-5 win.

That upped the Cardinals' record to 29-32, which is below their standards but still good enough to be in the chase in this year's version of the National League Central. Milwaukee enters the series in first place at 33-31.

The Brewers lost two of three over the weekend in Arizona, where even the win Friday night carried a price. Second baseman Jonathan Villar landed on the 10-day disabled list witha back injury.

Adding further insult to that ailment was a bullpen meltdown Sunday in an 11-1 defeat. The relief corps gave up 10 runs in the final two innings, breaking up a classic pitchers' duel between Milwaukee's Chase Anderson and Arizona's Robbie Ray.

"We've got more than one guy who is struggling right now, but they've got to pitch," Milwaukee manager Craig Counsell said of the bullpen. "The only way to get untracked is to pitch, and they've got to figure it out."

Counsell may have to turn to his bullpen early in the day part of Tuesday's twin bill. Scheduled starter Jimmy Nelson (4-3, 3.45 ERA) is 0-8 with a 7.09 ERA in his career against St. Louis. He lost to the Cardinals at Miller Park on April 23, when he gave up four runs (three earned) in 5 1/3 innings.

The Brewers hadn't announced a starter for the nightcap as of early Monday evening.

Lance Lynn (4-3, 2.88) will work the opener for the Cardinals. He got the win in his only appearance against the Brewers this year, pitching six innings of one-run ball April 22 at Milwaukee. Lynn has exceptional career numbers vs. the Brewers: 9-3 with a 2.31 ERA in 19 games (15 starts).

Left-hander Marco Gonzales will be called up from Triple-A Memphis to start the night game. He is 1-3 with a 3.26 ERA in five Triple-A starts this year. Gonzales got the win in his lone appearance against the Brewers, when he allowed one run in 2 1/3 relief innings.

He will be making his return to the majors after missing all of the 2016 season following Tommy John surgery.