ST. LOUIS -- The Cardinals’ grip on their division lead tightened ever so slightly the moment three Milwaukee defenders peeled off on what seemed a routine two-out popup Tuesday night. The ball dropped. The bases cleared. And the Cardinals parlayed the shot of momentum into a 9-4 win over the Brewers at Busch Stadium.

The immediate significance was obvious: The Cardinals increased their division lead over Milwaukee to four games while also maintaining a half-game advantage over the Cubs. But could it also be the start of something more?

• Box score

The Cardinals, who entered the night with a 53.8 percent postseason probability, per FanGraphs, have stayed afloat this season despite watching some of their best laid plans go awry. That included watching their Opening Day center fielder end up back in the Minors after losing his swing, and seeing a once-steady starter lose his command, then his rotation spot.

What Harrison Bader and Michael Wacha didn’t lose, however, was another chance to make it right.

Tuesday offered a glimpse of what-could-still-be if the Cardinals can squeeze more consistent production from a pair of players who can dramatically alter the look of this roster.

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“This is a fun time to be on this team right now,” Wacha said, after the Cards improved to 5-0 versus the Brewers at home this year. “We’re playing some really good baseball, and anything I can do to help is awesome. I want to be out there helping this team as much as I can.”

“I’m looking forward to going out there and getting after it,” added Bader, who made his first start since July 28. “I’m here to play, and I’m very excited about it.”

Fresh from his stint with Triple-A Memphis, Bader reached base four times, scored two runs and made a five-star catch that helped limit the Brewers’ scoring in the sixth.

Wacha, before being pulled as manager Mike Shildt sought to capitalize on a fourth-inning scoring opportunity, gave the Cardinals four shutout innings in his third start since being reinstated to the rotation. He struck out five and faced little resistance from a Brewers offense that had scored 24 runs over the weekend against the Nationals.

“Michael Wacha has demonstrated in high-leverage situations, the highest-leverage situations, to be a very, very effective Major League pitcher,” Shildt said. “The last three starts have been more than quality. Michael Wacha is a guy who is ready for the big stage, wants the big stage and has seen the big stage. So, if he pitches like he’s capable, we’re confident having him out there.”

It marked the first scoreless start for Wacha since June 10.

It had been nearly as long (June 24) since Bader reached base as many times as he did on Tuesday. Though his leadoff triple in the third was wasted, his patience paid off in a pair of ensuing four-run frames. Bader drew three of the team’s season-high nine walks, including a bases-loaded free pass that set the stage for Dexter Fowler’s back-breaking hit in the sixth.

“That’s just an unbelievable job by him accepting the assignment to Memphis with the attitude and then doing something about it,” Shildt said. “Some guys don’t handle that as well, or it takes a little bit longer. But he went down there roaring. [He] reset everything he was doing, and got back to where he is the quality player that we saw tonight.”

Fowler’s knock went into the box score as a three-run double, though the Brewers will contend it never should have touched the outfield grass. The batted ball registered with a 69.2 mph exit velocity and a .240 expected batting average, according to Statcast.

Bader, running hard as soon as Junior Guerra’s pitch broke Fowler’s bat, scored from first, as left fielder Ryan Braun, third baseman Hernan Perez and shortstop Orlando Arcia watched helplessly as the ball dropped between them.

"In hindsight, it’s either my ball or nobody's ball,” Braun said. “If I dive for it, maybe I catch it. I think I had the best chance to catch the ball.”

The insurance run Bader scored came a half-inning after he saved one by securing his fourth five-star catch of the season. His play on Keston Hiura’s sinking hit to center halted some growing momentum for the Brewers. Though Milwaukee went on to score twice in the inning, Bader’s ability to turn a ball with a 15-percent catch probability into an out assured that the Cards ended the inning trailing by only one.

St. Louis followed by moving to 10 games above .500 for the first time since it was 20-10 on May 1.

“He brings stuff to the game that a lot of players can’t,” Wacha said of Bader. “His skills can change games.”