PITTSBURGH -- Nothing felt amiss when Mitch Keller walked into the visiting clubhouse at Wrigley Field this afternoon. The energy was good. The vibes were loose.

“You would think we were on a five-game winning streak,” Keller said.

The Pirates didn’t enter Wednesday on a five-game winning streak. The night before, they were run out of the building. They lost by 13 runs, tied for their largest margin of defeat this season. The pitchers allowed four homers. The lineup struck out 16 times. Over the course of nine innings on Tuesday night, the Pirates were outclassed by the Cubs, a squad fighting for their playoff lives.

By the time Wednesday rolled around, all that happened the night prior ceased to matter. The rout had been flushed, and they were ready for a rout of their own, outslugging the Cubs, 13-7. They showcased not just their offense, but, as Keller describes, their resiliency.

“Showing up in the clubhouse today, everyone had flushed last night,” Keller said. “We knew we were going to be back on it. Some of the younger guys in the clubhouse, just really proud of them, how they flushed last night and came up and set the tone early.”

Pittsburgh and Chicago combined for five home runs, 20 runs and 27 hits, but in the early stages, pitching was the name of the game. Through three innings, Keller and Justin Steele engaged in a pitchers' duel, All-Star versus All-Star. Keller blinked first, allowing an RBI single to Seiya Suzuki in the second, but that was the only offense through three.

From there, as Keller describes, “all hell broke loose.”

The Pirates began the fourth with a sextet of singles to generate four runs, knocking Steele out of the game and, likely, out of the NL Cy Young Award race, too. After utilizing station-to-station baseball to score the first four runs, Joshua Palacios went with the long ball for the next three, sending a towering blast over the center-field fence. When Palacios touched home, the Pirates had a seven-run inning.

The Cubs, though, had a punch of their own to offer.

Following Jared Triolo’s solo home run in the fifth inning -- extending the lead to 8-1 -- Chicago responded with a five-run fifth against Keller, cutting Pittsburgh’s advantage to 8-6. Christopher Morel sent Keller’s cement-mixer sweeper onto Waveland Avenue to begin the inning, getting the home crowd back into the ballgame.

If Morel got the people going, then Ian Happ got the people jumping. Five batters later, with the bases loaded, Happ, the Pittsburgh kid, sent Keller’s 3-1, middle-middle four-seam fastball into the right-field stands. Wrigley went crazy. The game was on.

The Pirates’ offense, then, had a counterattack to the counterattack.

Following Chicago’s five-run fifth, Pittsburgh responded with a three-run sixth to quell any thoughts of a comeback. After Bryan Reynolds drove in Jason Delay with a force out, Connor Joe barrelled Mark Leiter Jr.’s four-seam fastball and sent the heater more than halfway up the left-field bleachers for a two-run home run, pushing the lead back to five. At 111.6 mph, the home run was Joe’s hardest-hit ball of the season.

That five-run lead was more than enough for the bullpen to work with. Following Keller’s departure with two outs in the sixth, Ryan Borucki, Carmen Mlodzinski, Colin Holderman and Hunter Stratton combined to pitch 3 1/3 scoreless innings with four strikeouts to one walk.

“One of the things I learned about our group today is they're not scared,” said manager Derek Shelton. “Last night, we got it handed to us, and they came right back out today with a bunch of young kids and kept their foot on the gas, and I'm really proud of them for that.”

Before offense ruled the day, Keller recorded his 200th strikeout of the season in the second, getting Dansby Swanson looking on a perfectly-placed backdoor sinker. Keller became the sixth Pirate since 1900 with at least 200 strikeouts in a season, joining Bob Veale ('64, '65, '66, '69), Oliver Pérez ('04), A.J. Burnett ('13), Francisco Liriano ('15) and Gerrit Cole ('15).

“It definitely means a lot,” Keller said. “A lot of hard work and perseverance. Even going back to last year, if you told me I’d be in this spot, I’d probably laugh and never believe you. Just a lot of people in my corner that keep pushing me and keep believing in me and keep going. I’m just glad I could do it and finish out the year strong.”