Poulin will serve as the Nationals' opening pitcher for Sunday's game against the Giants, Mark Zuckerman of NatsJournal.com reports.
Poulin will draw his third start of the season as an opener, again working in front of Miles Mikolas. The Nationals rode the Poulin-Mikolas pairing to a win over the Pirates on Tuesday, though the two pitchers combined to allow four earned runs over 4.1 innings. Poulin is unlikely to pitch more than an inning or two Sunday before turning the game over to the veteran right-hander.