ST. LOUIS -- Miles Mikolas might have picked up the win in his June 3 start against Chicago, but he had to grind for it. He made it through only five innings that day at Wrigley Field, and it took him 107 pitches to squeeze out 15 outs.

On Saturday at Busch Stadium, Mikolas wasn’t able to supplement his personal win-loss record, but the day went a little bit smoother for the starter. A back-and-forth eighth inning, with two runs scoring in each half of the frame, culminated in a no-decision for Mikolas but a 5-3 victory for the Cardinals.

Mikolas struck out nine Cubs and gave up one run on four hits and one walk in six strong afternoon innings under a sweltering sun, evening the second series of the month between the two clubs and keeping St. Louis tied with Milwaukee for the lead in the NL Central.

“[Went] back and checked out that video, see what I did wrong and what I can sharpen up,” Mikolas said of his approach between the two starts. “Look for some holes in their swings and their approach and stick to my guns as much as I can.

“Little up, down, in, out. Pitching 101.”

Juan Yepez doubled with one out in the bottom of the eighth against Chicago reliever Mark Leiter Jr., Harrison Bader was hit by a pitch and catcher Iván Herrera, the Cards' fourth-ranked prospect, drove a game-winning sacrifice fly to deep left field for his first career RBI.

“We don’t want a double play there in that situation, game tied in the eighth,” Herrera acknowledged. “We want that run to come in. Doesn’t matter how, but I gotta bring it home.”

Tommy Edman added an RBI single for insurance.

Ryan Helsley picked up his third win of the season in 1 2/3 innings of work from the bullpen.

St. Louis came precariously close to wasting the start with a missed opportunity in the bottom of the sixth and suffered some temporary heartbreak in the top of the eighth.

After an RBI double by Dylan Carlson that expanded the Cards’ lead to 3-1, Yepez flied out to shallow left, Harrison Bader struck out and Lars Nootbaar swung through a Scott Effross fastball. It was the second time in two days St. Louis had runners on second and third with no one out and left both stranded.

“Just need to take better at-bats in that situation,” Cardinals manager Oliver Marmol explained. “We had an opportunity to cash in a couple times and didn’t. We’ll be better moving forward.”

Brendan Donovan capped a two-out first inning for St. Louis with a two-run single, and Nolan Arenado also notched three hits and scored two runs.

The early June Mikolas start was his only hiccup in an otherwise stellar month. In his four starts since, he’s allowed only five earned runs and four walks over 29 innings while striking out 27.

“Mixed all [his] pitches, not that he doesn't do that every time,” Marmol said in assessing Mikolas’ outing. “I feel like the curveball was a big player for him, and then the guys you can beat up top, he exposed it.”

In that same span, Mikolas was saddled with two losses in games in which he received one combined run of support.

Saturday wasn’t much of an improvement on the scoring front, as the Cardinals managed to squeeze out only three runs with Mikolas still in the game against a Cubs staff fronted by Adrian Sampson in his first start of the season.

Four of the first five Chicago hitters in the batting order -- Christopher Morel, Rafael Ortega, Ian Happ and Patrick Wisdom -- were in the lineup for both Mikolas starts, with Willson Contreras slotting in for the injured Frank Schwindel.

That foursome combined for six hits against the righty in the game at Wrigley; facing Mikolas on Saturday, they mustered only a fifth-inning single by Wisdom, combining for seven of Mikolas’ nine strikeouts.

Once Mikolas was out of the game, though, damage was done against one of the most reliable pitchers in the St. Louis bullpen. With one out in the eighth, Morel singled against Giovanny Gallegos before Ortega delivered a two-run 371-foot bolt inside the foul pole in right field.

Mikolas had to pitch around very little traffic, at one point retiring 10 Cubs in order and allowing only a Contreras double in the game’s first four innings. Wisdom’s single led off the fifth, and after Nico Hoerner delivered his first of two hits, Wisdom scored on consecutive flyouts by Yan Gomes and Alfonso Rivas.

“He’s been a horse for us,” Marmol said. “Threw some really good gems, and today was another one.”