CHICAGO — Owen Caissie keeps things simple.

Like, really, really simple.

So simple that he said he blacks out on the baseball field.

Whatever the Cubs’ rookie outfielder is doing, it’s working.

Caissie has stepped up to fill in for the slumping Kyle Tucker and sparked the Cubs in an important victory in Game 1 of Tuesday’s doubleheader against the Milwaukee Brewers.

The 23-year-old drew the start in right field and drove in three runs — including his first career MLB home run in the sixth inning to give the Cubs a much-needed insurance run.

As he explained what was going through his head during the big moment, Caissie delivered a funny line akin to Frank the Tank from “Old School”:

“Kind of just black out, really,” Caissie said. “Especially on the home run — hit the ball and run. I didn’t even think about it going over the fence, especially with the wind. It’s just kind of a blackout mentality.”

[Check out the top highlights from Owen Caissie’s breakout game]

When Caissie went out to take his position in right field in the top of the seventh inning after the home run, the Wrigley Field faithful celebrated the team’s top prospect with a loud cheer and chanted his name:

Caissie also delivered clutch moments earlier in the game, with a two-out, two-run single in the first inning to allow the Cubs to breathe a sigh of relief. He then made a pair of nice running catches in the right field corner on tough plays in the third inning.

“He was the impact in this game that we needed today,” Cubs starting pitcher Matthew Boyd said. ” … It’s fun to be part of something bigger than yourself. We’re all happy for him that he got to do that today. And, you know, help us win a ballgame. It was awesome.”

The first-inning single was an example of how baseball can be cyclical. Caissie faced the same situation in Monday’s game — bases loaded — and struck out swinging.

But this time, he delivered a two-out knock to give his team an early lead.

Part of the reason he found success is because of a mindset that prepared him for the moment.

“I really just told myself, ‘you’re made for this and step back in the box and do a job,'” Caissie said after the game. “Because I’m going to have many more opportunities to do that. Today I got one, so I really embrace the challenge.”

Caissie acknowledged that those bases-loaded at-bats are quite a bit different in the major leagues compared to Triple-A. He is aware of the crowd and the energy, but he works to stay calm in the moment.

“Just stay grounded,” he said before Tuesday’s doubleheader. “It’s hard sometimes to not let the situation get big and honestly, just be who you are. Really just be in the moment.”

While Tucker works through his offensive struggles, the Cubs are hoping to give him a few days off as a mental reset.

That has opened the door for playing time for Caissie, who will start in right field again in Game 2 of Tuesday’s doubleheader.

The Cubs’ offense has been searching for a spark for some time now, and, for one game at least, Caissie provided that.

The organization’s top-ranked prospect was raking in Triple-A, posting a .955 OPS and 22 homers in 93 games before his promotion to the majors. He has been able to carry that success over early in the series against the Brewers and the Cubs hope that continues.

“Owen’s a hitter, and you see that by just the walk numbers and then it’s damage,” manager Craig Counsell said. “He hits the ball really hard. I think that opposite field homer gives you a pretty good example of that.

“Matt Shaw got into a ball pretty good and it didn’t get out [with the wind]. So he hits the ball really hard, and he can put the ball out of the park anywhere. That’s going to be real, and he’s going to get better at that as he gains experience.”