CINCINNATI -- Luis Castillo’s changeup? Still filthy. Pittsburgh hitters just couldn’t lay off of it.

To be fair, all of the Reds starting pitcher’s repertoire qualified as filthy on Wednesday night as Castillo cruised for seven innings during a 1-0 win over the Pirates at Great American Ball Park for a four-game series sweep. He allowed three hits and one walk while striking out 10.

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“Right now the clubhouse is just very, very happy,” Castillo said via interpreter Jorge Merlos. “We hopefully will continue on this run, and we'll be able to continue with this momentum and keep doing what we're doing.”

Cincinnati has won a season-high five games in a row and six of its last seven to move to one game below .500 at 25-26. It moved the Reds ahead of the Cardinals for second place in the National League Central, which is an automatic playoff spot in this shortened season.

“We're not trying to put too much pressure on ourselves. We've already done that,” catcher Curt Casali said. “We had those [expectations] in Spring Training and even into Summer Camp, and we fell short of that. But it doesn't mean that you can't bounce back from it. We're living proof right now we can put together a win streak.”

It hasn’t been the best season for Castillo, but like his club, he has gotten hot during this most important stretch. After he was 0-5 with a 4.10 ERA over his first seven starts, he is 3-0 with a 1.23 ERA in his last three, which includes a complete game his last outing, to lower his overall ERA to 3.03.

“The first month, maybe he wasn’t as dominant. It wasn’t bad either,” Reds manager David Bell said. “He was giving good efforts, he was giving us an opportunity to win. Clearly, he’s locked it in and we are at the end of the season now. Typically, he’d be on track -- if it was a longer season -- to keep going.”

The Reds' offense had its hands full with Pirates starter JT Brubaker until it put together a two-out rally in the fifth inning with three straight hits. Shogo Akiyama's RBI single to left field scored Jose Garcia to break the scoreless tie.

That one run was all Castillo would need. Not since his first start of 2020 -- July 25 vs. Detroit -- had he reached double-digit strikeouts. His changeup was responsible for six K’s -- all swings and misses. His sinker averaged 97.8 mph and his four-seam fastball averaged 97.6 mph, according to Statcast.

“I've been able to mix my pitches even better,” Castillo said. “Wherever I throw my fastball is where I'm throwing my changeup as well, so that's really confusing the batters a lot. That's what's really been working for me these past couple starts.”

That proved to be the case on Wednesday for Castillo as he threw his four-seamer, sinker and changeup in nearly equal totals among his 91 pitches. He also threw 14 sliders, including three in a row to strike out Kevin Newman in the fifth inning.

“I couldn’t imagine facing him from the right side of the plate,” Pirates switching-hitting first baseman Josh Bell said. “You know, his fastball has so much zip. His fastball is 98-99, so you have to honor it, and his changeup pops out looking the exact same. So he’s definitely one of the harder guys in the league to barrel up consistently. But we did. We just didn’t hit it in the right places at the right time."

Castillo and Casali have been particularly in sync with each other. In five starts together, Castillo has a 1.32 ERA, compared to a 5.33 ERA when Tucker Barnhart is behind the plate for him.

“I'm particularly proud of him because he's not just shaking immediately to his changeup,” Casali said. “His changeup is still elite. It's still probably the top two, three changeups in all of baseball, and he still gets a lot of strikeouts that way. But I think the last game in St. Louis, he finally got to taste a complete game. And that tastes pretty good.

"And I think he wants to go deep into ballgames and realizes that he's one of our best pitchers. And for him to go deep, he needs to keep his pitch count down. And when he keeps his pitch count down, it's early swings and then they end up striking out anyways. But it's been really fun to kind of go on this journey with him.”