ST. LOUIS -- With his seventh home run in eight games, Paul Goldschmidt not only broke the tie in the game, but also the tie in the standings.

Goldschmidt’s go-ahead homer in the bottom of the sixth inning Tuesday night vaulted the Cardinals to a series-opening 2-1 win over the rival Cubs and into sole possession of first place in the National League Central, after the two teams began the midweek series at Busch Stadium tied atop the division.

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The Cardinals separated themselves from the first-place tie ever so slightly. And while any win is important, there was no denying the fact that this series meant a little more to the teams and 46,123 fans in attendance -- the 15th sellout at Busch Stadium this season. It had a certain playoff feel, one that might be experienced as the season marches on with these two teams battling with the Brewers, who are two games back in third place after falling in Oakland late Tuesday night.

“Any time we’re playing the Cubs at home or at Wrigley, it’s going to be a lively atmosphere,” said Adam Wainwright, who threw 5 2/3 innings in his start. “We’re almost in August now, we’re right there at the top of the division, and they’re a game back now. It’s going to be fun. The fans, there was a buzz in the crowd today that I really loved.”

Goldschmidt’s tie-breaking home run was just one key moment that put the Cardinals in a position to win. The 392-foot home run was his team-leading 25th of the year and gave him 11 homers and 27 RBIs over his last 21 games. That accounts for nearly half of his total RBIs this season (58 in 106 games).

And it came against an unlikely target. Goldschmidt was hitting just .071 (1-for-14) with nine strikeouts in his career vs. Cubs starter Yu Darvish before Tuesday night. After his single in the fourth inning, Goldschmidt took a 1-1 two-seamer inside over the left-field wall the third time he came to bat.

“I was just trying to get a pitch in the middle of the plate and stay short to it,” Goldschmidt said. “I didn’t want to foul off a good pitch to hit because he’s got strikeout stuff. It’s really, really good, so you may only get that one pitch per game or at-bat.”

Gallegos strands them again

For Goldschmidt’s tiebreaker to happen, Giovanny Gallegos had to face lefty Kyle Schwarber with two outs and the bases loaded in the top of the sixth inning. Cardinals manager Mike Shildt turned to the right-hander after Wainwright gave up a double and two walks, one intentional.

Shildt had two left-handed relievers, Andrew Miller and Tyler Webb, ready to face Schwarber, but he thought that the Cubs might pinch-hit. At that point, though, he didn’t mind what direction the Cubs went because the Cardinals had Gallegos -- effective in bases-loaded situations no matter the batter all year. And he got Schwarber to fly out.

“We got a guy that’s effective the same against lefties and righties,” Shildt said. “At that point, we don’t mind what direction they go, we trust Gio to throw strikes.”

Gallegos has faced 13 batters in bases-loaded situations and hasn’t allowed one of them to score. But it’s just another day’s work for him.

“I don’t think too much when I’m in those situations,” Gallegos said. Strike out the hitter.”

Martinez seals it

The Cubs threatened again in the top of the eighth inning after Miller walked two batters with two outs. So Shildt called on closer Carlos Martinez to face Ian Happ, not wanting to take any chances in a one-run game with a lot on the line.

“It definitely had a playoff feel to it,” Shildt said. “I thought the series over the weekend [against Houston] had a playoff feel to it. We love it.”

Happ chased an 88-mph changeup, and Martinez finished off the game, striking out two in the top of the ninth to earn his 11th save this season and seventh since taking over the closing job from Jordan Hicks.

“I knew I had two men on base, and he’s a good hitter against me, so I know ... I needed to throw my best pitch in that situation,” Martinez said. “That pitch was my changeup. I had good focus and relaxed my mind.”