Detwiler will face on the Yankees on Monday and Strasburg will start Tuesday against the Braves.
The reliever's chance of earning a bullpen spot may suffer a setback.
Ryan Mattheus will receive an MRI today to determine the severity of a chest injury that has put him on hold.
The four pitchers, from starters to relievers, will have stiff competition for spots on the team.
The right-hander has a 7.27 ERA and believes his approach and stuff haven't been sharp.
Also, more on Johnson's fears of Ross Detwiler's hope to return this season.
The left-handed starter may not return this season, Davey Johnson says. The right-handed reliever was recalled just before Tuesday's game.
After three strong weeks at Class AAA, Storen returns to the majors.
The right-hander returns for the doubleheader but could stay longer.
Ryan Mattheus will move his rehab assignment to Class AAA as many roster choices loom for the Nationals.