DeJong took Wilson (1-1) deep on a 2-2 slider to make it 3-2.
"I knew he has a lot of stuff that goes away, a little slider, a little cutter and I wasn't looking to pull him," DeJong said. "I just went with the slider away. I rolled over a slider last night. I knew I wanted to see him deeper in the count, and I just got off a good swing off."
The Cardinals have won four in a row. The Brewers have lost five of six.
Molina hit his second double with one out in the eighth, scoring Jose Martinez, who had walked to go with two singles. Molina stole third but was stranded there. It was his first stolen base this season and the 17th time he's stolen third in his career.
"We're doing a pretty good job being aggressive and taking extra bases," Molina said. "That's what part of our game is right now, we're going to take advantage of what they give us."
Andrew Miller (1-1) struck out two in a perfect eighth to pick up his first win as a Cardinal. Miller's last victory was on Aug. 9 against Minnesota, and the two-time All-Star has a disappointing 6.23 ERA this season.
"That was Andrew Miller tonight," Cardinals manager Mike Shildt said. "He had a really filthy slider. It's a pitch that's hard to contend with. With his fastball, that's pretty lethal combination."
Jordan Hicks pitched the ninth for his sixth save. Shaw led off the ninth with his second home run. After a walk, Hicks got a strikeout and a double play.
"We put together a decent ninth against Hicks," Milwaukee manager Craig Counsell said. "It just wasn't enough."
Arcia belted a homer to center to lead off the fifth and tie it at 1. Shaw's homer off reliever John Gant tied it at 2 in the sixth. Shaw also homered in Monday's series opener when he snapped an 0-for-17 skid.
"We're playing good teams," Shaw said. "We need to keep our head above water and hopefully finish out this trip well."
St. Louis starter Daniel Ponce de Leon, who was activated before the game, started in place of the injured Michael Wacha. In his season debut, Ponce de Leon pitched five innings, striking out seven and allowing two hits and one run.
Milwaukee starter Zach Davies pitched 4 2/3 innings. He gave up seven hits and two runs.
CARLOS MARTINEZ UPDATE
Cardinals RHP Carlos Martinez, out with right shoulder cuff strain, has missed 23 games. He threw a side session Tuesday. He's up to 30 pitches of moderate-to-high intensity. He will throw again Friday and likely one more session after that, Shildt said. When he comes back, it will be as a reliever.
Cardinals: INF/OF Drew Robinson, who was recalled from Triple-A Memphis on Monday, was sent back down Tuesday to make room for Ponce de Leon.
Brewers: RHP Freddy Peralta (right shoulder inflammation) will throw a full bullpen session Wednesday. His 15-pitch light bullpen Monday went fine, the Brewers said. He could rejoin the rotation in the next homestand, which begins Monday against Colorado.
Cardinals: OF Harrison Bader (right hamstring strain) ran the bases before the game. He is expected to be activated from the injured list before Wednesday's game. ... OF Tyler O'Neill (right ulnar nerve subluxation) was set to begin his rehab assignment Tuesday night in Double-A Springfield. He will play three games there and get four at-bats in each. ... RHP Luke Gregerson (right shoulder impingement) visited with team doctors Tuesday and will returning to Doube-A Springfield. He will be used out of the bullpen as a regular reliever instead of structured work.
Brewers: Jhoulys Chacin (2-2, 5.92) will be making his second start this season against St. Louis.
Cardinals: Adam Wainwright (1-2, 4.74) pitched a season-high seven innings in his last start (April 11) against the Brewers.
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