Tanner Roark will take the mound with the Nationals facing elimination in Game 4. (Jeff Roberson/AP)

CHICAGO — Tanner Roark was born and raised in Wilmington, Ill., which is southwest of Chicago, which means he grew up closer to Comiskey Park than to Wrigley Field. But geography didn’t impact baseball team allegiances in the Roark household. He grew up a die-hard Cubs fan like his mother and siblings, diverging from his father’s loyalty to the White Sox and the Cardinals.

“Growing up, yeah, there was always some trash-talking in the house between us and my dad,” Roark said.

On Tuesday, barring rain, Roark will find himself on the mound at Wrigley Field, the ballpark he visited countless times as a fan, to face the Cubs. It won’t be his first start there; he has four on his résumé and appeared in another game out of the bullpen. But none of the previous outings carried the same weight Tuesday’s will place on Roark’s right arm: Game 4 of the National League Division Series with his Nationals facing elimination.

“It’s pretty surreal to pitch in Wrigley, and just the history that they have here and everything,” Roark said. “It’s very exciting, and I’m anxious to get out there.”

Roark hasn’t pitched since the Nationals’ regular season finale on Oct. 1, when he allowed two runs in an inning of relief against the Pirates, and he hasn’t started a game since Sept. 27. He lasted 4 2/3 innings that day, surrendering six runs on seven hits to the Phillies. But Roark was significantly better before the poor finish; he had posted a 3.39 ERA in 57 innings over his previous nine starts to rebound from an inconsistent four months after his stint with Team USA at the World Baseball Classic made for an unusual spring training.

“Tanner didn’t have many innings coming out of spring training, and that kind of got him behind the eight-ball, so to speak, because you know, he didn’t have the innings,” Nationals Manager Dusty Baker said. “He was with the WBC and he didn’t pitch very much. And so things get in your head when you’re used to getting guys out and all of a sudden you’re not getting them out. So it’s a new season now for Tanner, brand-new season, and this is what people are going to remember you by.”

Roark’s playoff experience includes two relief appearances in the 2014 NLDS against the Giants and a start against the Dodgers last year, which ended after yielding two runs on seven hits in just 4 1/3 innings in Los Angeles. He’ll rely on his two-seam fastball and, with Matt Wieters behind the plate, his the unorthodox pitch sequencing to continue the postseason dominance of the Nats’ starters: Through three games, Washington starters have allowed six runs — four earned — across 18 1/3 innings. Two of them — Stephen Strasburg  and Max Scherzer — have carried no-hitters into the seventh inning. The Nationals lost both games.

“Tanner, you know, is a guy that you would like on your side if you’re in an alley and you’re in a fight, because you know Tanner, he has that warrior mentality,” Baker said. “He doesn’t make any excuses or alibis. He just goes out and pitches, and this guy has not had an easy road, you know, from the beginning to get here. We feel very comfortable with Tanner on the mound because you know he’s going to fight tooth and nail and do everything he can to win the ballgame for you.”

Roark recalled 300 people from Wilmington congregated in a section in right center field for his Wrigley Field debut in 2013. He doesn’t expect that again Tuesday. He hasn’t been hounded for tickets. Five relatives, his wife, and their two children will be in attendance to watch his biggest game of his career.

“They are good about getting their own tickets,” Roark said, laughing. “Which is very good on me. It’s a lot less stress that I have to worry about.”

More on the Nationals:

Nationals pushed to brink of elimination after wasting Max Scherzer’s Game 3 gem

Boswell: Plenty of decisions to second-guess in Game 3, but that doesn’t mean they were wrong

Dealt a bad hand, Max Scherzer still looks like an ace in Game 3 loss to Cubs

Best and worst moments from the Nationals’ 2-1 loss in Game 3

New York Mets to purchase the Nationals’ Class AAA affiliate

When did Mike Rizzo become a Cubs fan? In the summer of ’69.