The Nationals placed Doolittle on the 10-day injured list Thursday with right knee fatigue, Brittany Ghiroli of The Athletic reports.

EDGE Analysis

Expected to challenge Daniel Hudson for the closer's role in the abbreviated season, Doolittle hasn't been able to reclaim his old post while giving up at least one run in all but one of his five appearances on the campaign. The lefty's fastball velocity has been down a few ticks this season, but it's unclear if his struggles are simply age-related or a byproduct of overcompensating for the sore knee. The Nationals are hoping it's the latter, as Doolittle will now be sidelined for at least the next week and a half before the team revisits bringing him back onto the 28-man active roster. Seth Romero was called up from the Nationals' taxi squad in a corresponding move.