Littell is slated to follow an opener in Monday's game against the Guardians, Spencer Nusbaum of The Athletic reports.
Left-hander PJ Poulin will open things for the Nationals before Littell carries the bulk of the workload. Littell had a rough April but has settled in in May, posting a 2.55 ERA, 0.96 WHIP and 7:4 K:BB over 17.2 frames covering two starts and two bulk relief appearances.