The loss evens the weekend series at one game apiece, knocks St. Louis seven games back in the National League Central and sets up a pivotal rubber match Sunday.
Saturday's showdown wasn't as out of reach as the scoreline might presume. The two sides were knotted at 1 after five frames before the Cardinals surrendered a three-run sixth inning and a four-run seventh to snap the club's four-game winning streak.
Cardinals starter Jaime Garcia fared well through the first five innings, holding the Reds to one run on four hits while striking out five before watching things unravel in the sixth.
The 26-year-old righty surrendered a leadoff double to Brandon Phillips followed by a lined single to Ryan Ludwick. Todd Frazier drove in Phillips on an infield grounder, beating out the double play on a close call at first base.
Whether he was irritated by the call or the lack of execution, Garcia was visibly frustrated after the Cardinals failed to turn two on the play. The questionable call proved costly as Garcia gave up a two-run homer to Jay Bruce one batter later to push the Reds' lead to 4-1.
"It's a little frustrating when you're out there, but it's part of the game," Garcia said of the missed opportunity. "That's not the reason why I gave up the home run. I made a mistake up in the zone and paid the consequences. Those guys were swinging the bat good."
The Cardinals managed to cut the lead in half in the seventh inning, stringing together three base hits off Reds starter Mike Leake. Shane Robinson pinch-hit for Garcia and grounded into a 6-4-3 double play that scored Tony Cruz from third to make the score 4-2.
"Every time you play the Cardinals, you've got to go out there and just know that team is special," said Phillips, who sparked the second Reds streak of the afternoon. "You see the guys, all of them are hitting .300. I don't know who is making the outs on that team. They're a great team."
With the door still open for the Cardinals to take the first two of the three-game series and begin their steady climb back into the division hunt, they sent Brandon Dickson to the mound in the bottom of the seventh.
Dickson shut down the first two Reds he faced but allowed the ensuing six hitters to reach base via hit or walk in a four-run two-out rally anchored by a Phillips home run and RBI singles from Scott Rolen and Dioner Navarro.
With two away, Dickson had Phillips, Frazier, Rolen, Navarro and pinch-hitter Chris Heisey all down to their final strike but couldn't shut the door on the inning.
"He gets the two outs, then just has trouble finishing it up there," said Cardinals manager Mike Matheny. "Actually, there were a couple times when he was 0-2 and that put-away pitch was just kind of eluding him. It was a tough inning. You hate seeing one of our guys stay out there that long and throw that many pitches, but we needed him."
The Cardinals nearly matched the Reds hit for hit, finishing one shy of Cincinnati's 12 knocks, but failed to get the crucial hit when needed.
"We were absolutely in that game," Matheny said. "When those close games come around you have to do the little things. You have to do the situational hitting, get the bunts down, you have to be smart baserunners ... or else you're going to end up on the bad end of those close ones."
All is certainly not lost for the Cardinals, as they aim to take the series from their division rivals before traveling to Pittsburgh and Washington heading into September.
"Every game is tough for us," Matheny said. "Today was a big day, and tomorrow will be a big day. We're very clear with our mission, and we've got to play good baseball every night."