– Maybe it's time to stop treating the Chicago Cubs like they're too young to be here.

The stage they seemingly weren't ready for now seems hardly big enough to contain them. Not with Jake Arrieta dealing. Not with a group of 20-somethings in the field who play with swagger and confidence. Not with a manager adept at keeping the minds of his rapidly maturing team decidedly clutter-free.

Watch out, baseball, the Cubs are ahead of schedule. And the timetable only seems to be picking up speed for manager Joe Maddon's bunch.

Arrieta allowed four hits in nine dominant innings and Chicago rolled to a 4-0 win over the Pittsburgh Pirates in the NL wild-card game on Wednesday night. Arrieta struck out 11 without a walk. He also dusted himself off getting plunked by Pittsburgh reliever Tony Watson to send the Cubs to the NL Division Series in St. Louis starting on Friday.

"I'm exhausted. I haven't felt this way all year," said Arrieta, who led the majors with 22 wins. "This atmosphere, the energy was unbelievable. Tried to use it to the best of my ability. They were loud, they were really loud."

Dexter Fowler homered and scored three times for the Cubs. Kyle Schwarber, a rookie who began his season in Class AA, added a towering two-run shot off Pittsburgh starter Gerrit Cole as Chicago raced to an early lead and let Arrieta do the rest.

"Jake told me when we talked last night, he said, 'You give me a few runs, I'm good,' " Fowler said. "And I said, 'All right, bro, we'll see what we can do.' "

The largest crowd ever at PNC Park (40,889) failed to rattle Arrieta or one of baseball's youngest teams, one that looked right at home while ending a nine-game playoff losing streak that dated to the 2003 NLCS.

"You don't think that these guys are 21, 23 years old, because they don't play like it," Arrieta said. "They have elevated their play to a level that's beyond their years, and it's one of the big reasons we're here."

Sounds a lot like the Houston Astros, by the way. They opened this year's postseason Tuesday night by winning the AL wild-card game at Yankee Stadium.

Pittsburgh was knocked out after finishing second in the majors with 98 victories. Last season, the Pirates also were shut out on four hits at home in the wild-card game, losing to Madison Bumgarner and the San Francisco Giants.

"Two years in a row we've drawn a tough bull," said manager Clint Hurdle.

Arrieta, still unbeaten since July 25, stretched his remarkable second half — in which he posted an 0.75 ERA — into the opening round of the playoffs. He threw the first complete-game shutout for the Cubs in the postseason since Claude Passeau tossed a one-hitter in the 1945 World Series against Detroit.

Arrieta retired 10 straight at one point, his only real wobbles coming in the sixth and seventh. Pittsburgh loaded the bases with one out in the sixth behind a single, a hit batter and an error.

Starling Marte's sharp grounder, however, rolled right to Addison Russell at shortstop. A toss to second and a throw to first completed the double play, and Arrieta was pumping one of his fists on the way back to the dugout.