Chicago Cubs pitcher Jake Arrieta was expecting to get hit after hitting Pittsburgh Pirates pair Francisco Cervelli and Josh Harrison in consecutive innings during the National League (NL) wildcard game.

The Cubs won their first play-off since 2003 as they shutout the Pirates 4-0 in a tense NL encounter on Wednesday.

Arrieta, who became the first pitcher in MLB post-season history to throw a complete-game shutout with at least 10 strikeouts and no walks, nicked Cervelli's hand in the fifth, then hit Josh Harrison in the shoulder in the sixth.

Whether intentional or not, those drew the ire of the Pirates, and reliever Tony Watson retaliated by plunking Arrieta in the hip in the seventh. That led to the benches emptying.

Speaking afterwards, Arrieta said: "I anticipated that.

"It's just one of those situations where you expect Tony to protect his guys."

Watson's plunking of Arrieta led to the benches emptying and the ejection of Pittsburgh's Sean Rodriguez, who appeared to throw a punch at David Ross.

Rodriguez said after the game that Ross tried choking him in the scrum.

Arrieta is not holding any grudges, at least publicly, against the Pirates. 

"It's two teams battling, grinding it out, supporting their own guys, and sometimes those things happen," Arrieta explained.

"But we moved past it, and after that point it was just baseball as usual.

"The two, two-hit batters were unintentional. In those situations, there's no way I'm trying to put guys on base with hit batters. The balls were pretty slick tonight. A couple got away from me. It kind of ran up and in on me. One was a slider, so just kind of spun."