Castillo will serve as the opener Saturday against the Marlins, Marc Topkin of the Tampa Bay Times reports.

EDGE Analysis

Castillo worked as an opener last Friday for the first time this season and delivered a perfect first inning. The 25-year-old has a 3.73 ERA, 1.37 WHIP and 47:19 K:BB through 41 innings and is 8-for-9 in save opportunities working in a flexible role for the Rays.