Orioles right-hander Jake Arrieta made a huge push toward solidifying his case for the team’s fifth starter spot on Thursday night, tossing six shutout innings against the Pittsburgh Pirates -- his third straight scoreless Grapefruit League outing -- at Ed Smith Stadium.

Arrieta hasn’t allowed a run over 14 2/3 innings in his past three spring outings. He allowed an unearned run in an exhibition start against Spain’s World Baseball Classic team in the outing before that stretch.

In five Grapefruit League outings, Arrieta has allowed just three earned runs and 11 hits, recording a 1.56 ERA with 16 strikeouts and eight walks.

As the final week of spring games approach, Arrieta is entrenched in battle with Steve Johnson, Brian Matusz and Zach Britton for the No. 5 spot in the rotation. But Arrieta’s six-hit, nine-strikeout, two-walk performance against the Pirates has to make him the frontrunner.

For his second straight start, Arrieta battled through adversity to keep a shutout intact. He stranded five runners in scoring position on the night.

In the fourth, the Pirates had two runners on and one out before Arrieta struck out Brad Hawpe and Clint Barmes to end the inning. With runners at the corners and one out in the fifth, Arrieta struck out Pirates cleanup hitter Pedro Alvarez and Garrett Jones flied out to right to end the inning.