ST. LOUIS -- For the last five years, the Cardinals and Pirates have played as close as any two teams in baseball. The National League Central rivals have gone win for win, practically run for run. So it was hardly a surprise Saturday afternoon when the Cards, having dropped their first four matchups with the Bucs this season, punched back in a 6-4, walk-off victory.
Matt Carpenter ended the back-and-forth affair with his first career walk-off home run, a two-run shot to right-center field off reliever A.J. Schugel in the ninth. Rookie shortstop Aledmys Diaz hustled out an infield single to lead off the inning, and Carpenter came to the plate with one out. The Cards' third baseman crushed a 1-2 changeup to right-center field, setting off a celebration at Busch Stadium.
• Cast your Esurance All-Star ballot for Carpenter and other #ASGWorthy players

"It's awesome," Carpenter said of his first career walk-off homer. "Being able to win the game like that, especially with the way it kind of played out beforehand, it was a big win."
Just how evenly matched are these two clubs? Pittsburgh and St. Louis have played 62 regular-season games since the start of the 2013 season. Each team has won 31 games, an even split.
With Saturday's game tied and one out in the eighth, right fielder Stephen Piscotty -- who also homered in the third inning -- ripped a double to left field off Pirates reliever Jared Hughes. Randal Grichuk then knocked a two-out, ground-ball single to center field off Hughes, putting St. Louis back on top.
• Young outfielders Grichuk, Piscotty come through for Cards

But Starling Marte's ground-rule RBI double off Cardinals closer Trevor Rosenthal evened things up in the top of the ninth. The Pirates might have won the game on that hit, or at least taken the lead, but since it bounced over the wall, Gregory Polanco -- representing the go-ahead run -- was stopped at third base, where he was stranded.
"You think just a hit in the gap would have brought Polanco in," Marte said. "It's OK. Things happen, and we continue on."
• Unlucky bounce on Marte double changes game

Diaz hustled out an infield single to lead off the bottom of the ninth against Pirates reliever A.J. Schugel. Carpenter came to the plate with one out and crushed a 1-2 changeup to right-center field, the first walk-off homer of his big league career.
After each team scored two runs in the first inning, both starters -- the Cardinals' Adam Wainwright and Pirates' left-hander Jeff Locke -- settled down considerably. Wainwright retired 14 consecutive batters at one point and left having allowed three runs in 6 1/3 innings. Locke recorded his third straight quality start, permitting three runs in six innings and sitting down the final 12 batters he faced.
• First inning once again Wainwright's only issue

"It settled into a well-pitched ballgame until the seventh," Pirates manager Clint Hurdle said. "Then the runs started coming again."
MOMENTS THAT MATTERED
Quick strike: The Pirates went right to work against Wainwright, as each of their first four hitters picked up a hit to begin the game. John Jaso singled, Andrew McCutchen doubled, Polanco hit a bloop RBI single and Marte singled to center before Wainwright could record an out. Wainwright promptly retired the Bucs' next three hitters, but they tacked on another run on Jung Ho Kang's sacrifice fly to right field.

Grichuk comes through: Entering the game in the midst of a 3-for-31 slump, Grichuk came up with a pair of key singles. After tying it in the first, Grichuk broke a 3-3 tie with a two-out single in the eighth scoring Piscotty. It was Grichuk's third go-ahead hit of the season.
"Two huge hits," Piscotty said. "I think that's going to get him really rolling. That's big, especially against the Pirates."

Rapid response: The Cardinals wasted no time digging out of their early hole in the first inning. Aided by a pair of walks, the first three hitters in the bottom of the first loaded the bases for Grichuk, who delivered a two-run single to tie the game. Wainwright settled down after a shaky first, retiring the next 14 Pirates hitters he faced after a leadoff hit by Jordy Mercer in the second.
Making new memories: The last time reliever Neftali Feliz pitched at Busch Stadium: Game 6 of the 2011 World Series. That was when Feliz, the fireballing Rangers closer, fell victim to David Freese's game-tying triple to right field with Texas one strike away from a championship. More than four years later, with Freese now a teammate on the Pirates, Feliz pitched a scoreless seventh inning against the Cardinals -- and perhaps fittingly, the last out was a fly ball to the right-field warning track.
• Freese makes first return to St. Louis since exit

Freese made his first appearance at Busch Stadium as a visiting player, pinch-hitting in the ninth inning. The crowd of 42,338 responded with a standing ovation for the hometown hero, who tipped his helmet to the fans.
QUOTABLE
"He's out there fighting. He wants to make a difference and strengthen this rotation. The last three starts are indicative of the focus and the intent and execution and conviction he's pitching with." -- Hurdle, on Locke, who has made three straight quality starts
"Wasn't that awesome they were so excited I struck out Cervelli there? The crowd went crazy. They really were behind me right there." --Wainwright, on the fog horn going off signaling a Blues playoff goal after he struck out Francisco Cervelli in the first inning

SOUND SMART WITH YOUR FRIENDS
Wainwright smashed a ground-rule double into the left-field corner during his first at-bat in the second. It was his fourth straight extra-base hit following a triple, homer and another double. According to Elias, Wainwright is the first Cardinals pitcher in the modern era (since 1900) to have an extra-base hit in four consecutive at-bats.

UMPIRE CHANGE
After the second inning, the umpires were forced to change their rotation. Home-plate umpire Dana DeMuth left the game after taking a foul tip off his mask. Ed Hickox, who began the game as the second-base umpire, moved behind the plate after an 11-minute delay to change into the home-plate gear.
DeMuth, who missed the rest of the game, entered the league's protocol for potential head injuries, Major League Baseball announced.
WHAT'S NEXT
Pirates: Right-hander Gerrit Cole will start for the Pirates as they wrap up this series with the Cardinals on Sunday at 2:15 p.m. ET at Busch Stadium. Coming off a rough outing in which he admittedly felt out of sync, Cole will try to get back on track against the Cardinals. Cole is 4-3 with a 2.91 ERA in eight career starts against St. Louis. With Kang likely getting the day off, Freese is expected to start at third base.
Cardinals:Michael Wacha (2-2, 2.65 ERA) hopes to toss his fifth consecutive quality start in the finale of the three-game series Sunday at 1:15 p.m. CT. Wacha shares the National League lead with five quality starts. He is winless in his last two, a victim of no run support as both were shutout losses.
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