CHICAGO -- As the baseball disappeared into the bushes beyond the ivy-covered wall in center, Nico Hoerner clenched both fists and let out a celebratory scream. The crowd inside Wrigley Field howled along with the rookie in another milestone moment in his first week in the big leagues.

Hoerner's shot to center in the first inning of Friday's 17-8 victory marked his first home run in the Majors, and it helped fuel a 10-run outpouring of offense in the first three frames against the Pirates. The blast came on the first pitch of the first at-bat of Hoerner's career in front of the Wrigley faithful.

"It's not what I expected to be doing this week," Hoerner said. "But, it's obviously the best week of my life."

And those comments came a couple of hours before Hoerner rocked the Friendly Confines with his go-ahead, two-run shot off Pirates lefty Steven Brault. And well before he helped keep the offense churning with a two-run single in the fifth.

Hoerner also became the first Cubs player since Andy Pafko in 1943 to record eight RBIs in the first five games of his career. With four more RBIs on Friday, Hoerner is also the first Cubs player since at least 1908 to have multiple games with at least four RBIs within his first five career games in the Majors.

"I asked him how good it feels to hit a homer on the first pitch," Cubs catcher Willson Contreras said. "He said, 'Oh man, this is amazing.' I said, 'Hey, congratulations. I know this makes a big impact on your life. It's crazy. You were home and then you got called up and then you start doing all these special things. And I know you can help us.' Nico is going to be a good player for us, for sure."

Five days ago, the 22-year-old Hoerner was at home in California when the Cubs buzzed his phone. Chicago's No. 1 prospect (per MLB Pipeline) was in a down period between his season with Double-A Tennessee and heading to the Arizona Fall League. Heading to the Major Leagues was the furthest thing from the shortstop's mind.

Things changed on Sunday, when shortstop Addison Russell was hit in the head by a pitch in the Cubs' game against the Brewers in Milwaukee. All-Star shortstop Javier Baez was already out with a hairline fracture in his left thumb and will be sidelined at least through the end of the regular season. At Triple-A Iowa, Dixon Machado was hurt and Zack Short was coming off a health issue of his own.

"We weren't planning on bringing him up this year," Cubs president of baseball operations Theo Epstein said before Friday's game against the Pirates. "We decided that Nico, given his mental makeup, that he could handle it, even if it was a lot earlier than we thought, just because he's such a thoughtful kid. He's highly intelligent. He's got great emotional intelligence as well. Self-aware.

"I think going into an environment where winning is the obvious priority at the moment, that fits his mindset, because he's always just looking for ways to help the team win and be part of the group. He's done that so far. He's gone out and he's showed off his tools and his composure, so it's been a nice start for him."

Last summer, Hoerner made a trip to Wrigley Field while sidelined with an elbow injury. Fresh off being picked in the first round of the 2018 MLB Draft out of Stanford, it gave him a chance to see his future ballpark and to meet some potential teammates, coaches and manager Joe Maddon.

"Have you spoken with him yet?" Maddon said. "His personality, his makeup, he's a really well-thought-out young man. A lot of self-confidence. He doesn't carry a lot of doubt with him. ... Plus, he's good. He's good. He's got good hands. He makes contact. He can hit a variety of different kind of pitchers. He's got all that going on for him."

The Cubs knew they could expect that kind of composure, confidence and energy from Hoerner.

But what about that Major League debut on Monday in San Diego?

"That type of unreal debut is never to be anticipated," Epstein said with a smile. "That was such a magical night."

In his first game in the Majors, Hoerner churned out three hits and drove in four runs, including two on a triple in the fifth inning in San Diego. He did so with a host of family and friends in the stands at Petco Park. For Friday's game at Wrigley Field, Hoerner said a few family members and close friends made the cross-country journey to watch his first game in Chicago.

"It's definitely a second debut of sorts," Hoerner said. "It's just continuing to do what I've done the last four days, and my whole life. I'm really lucky to be on a team that's focused on winning right now. It kind of takes the personal side out of it a little bit. Having that bigger result as the priority helps the personal things fall in place."

Maddon said he has not been surprised at all by Hoerner's poise on baseball's biggest stage in the middle of a postseason race.

"Why he can do this? It's because of him. The innate components of his being," Maddon said. "He's just a solid young man that believes he belongs here and that's why he's doing so well."