ST. LOUIS -- Matt Carpenter swung hard and missed at two splitters in the bottom of the zone from Reds reliever Kevin Gausman, but he knew what was coming next.

He was ready for it.

When Gausman threw the next splitter in the same location, Carpenter swung and made contact, hitting a shallow single to right field that was enough to score Yadier Molina from second base and seal the Cardinals’ 3-2 walk-off victory and doubleheader Saturday, after having won the afternoon contest, 10-6. It was the first doubleheader sweep at Busch Stadium since June 8, 1992, against the Cubs.

• Box score

“I wasn’t trying to do more,” Carpenter said. “Three-run homer -- you still win the game either way with a base hit. I was just trying to put a good swing on it and get a pitch up that I could hit a line drive on. The big thing is being in control of my emotions in that situation, and having been in that spot before, taking a good swing and having a competitive at-bat in that spot and not letting the moment get to you.”

The elation that followed Carpenter’s seventh career walk-off hit and second this season was the culmination of a winning month for the Cardinals and the feeling that they’re hitting their stride at exactly the right time.

“Not really concerned about the calendar, we just keep playing games,” manager Mike Shildt said. “But it was a good day for us for sure.”

St. Louis finished August 18-9 -- tying April with the most wins in a month for the club this season -- and in first place in the National League Central, 2 1/2 games ahead of the second-place Cubs.

“We’ve got a good club that’s doing everything we need to do and we’re hitting a good stretch of what we thought we were capable of doing all year,” Carpenter said. “The timing of this is perfect. We’re playing our best baseball late, and hopefully we can ride it to the end of October.”

The Cardinals’ capabilities are showing up and down the lineup, throughout the rotation and in the bullpen. Everyday players and bench players have contributed to the winning month and recent surge that the Cardinals have put together.

On Saturday night, the ninth-inning comeback began with Tommy Edman’s leadoff single and continued with Molina’s hit by pitch. Harrison Bader’s single to left field tied the game with Carpenter on deck to pinch-hit. Molina and Carpenter didn’t start the second game, but they made sure to leave an impact on it.

“Everyone knows where we’re at in the season,” said Cardinals starter Michael Wacha, who gave up two runs in seven innings in one of his best starts of the season. “So everyone comes to compete every day.”

“This is a team -- everybody in here that’s got a locker is contributing in a big way,” Carpenter said. “There’s nobody taking up space. That’s rare on a big league team. You usually got somebody or a couple guys that are just around. That’s not the case here. We play everybody, we use them every night. The manager can write out a different lineup every night and feel confident about going out there and winning the game.”

That depth will come in handy over the last month of the regular season, but especially over the next couple of days. The Cardinals have a chance to do what they did Saturday again on Sunday, with another doubleheader against the Reds scheduled at Busch Stadium.

While Shildt juggles the different lineups, matchups and giving players the rest they need, he doesn’t have to worry about a lack of contribution from anyone he plugs in.

“When you play doubleheaders back-to-back days, you’re going to see a bunch of different lineups,” Carpenter said. “If anybody’s built for it, we are.”