Castillo will serve as the opening pitcher for Friday's "bullpen day" game against the Athletics, Marc Topkin of the Tampa Bay Times reports.

EDGE Analysis

Castillo has been on a roll in September, allowing just one earned run on three hits and two walks over six innings while recording six strikeouts. The 24-year-old right-hander is slated to give way Ryan Yarbrough after what most likely will be two frames at most Friday.