Johnson suffered a setback two weeks ago, when he still felt soreness in his wrist after the cast was removed. The wrist was then re-cast for an additional two weeks. Johnson has been on the disabled list since May 15 because of a torn tendon sheath inside the wrist. He hurt his wrist during his last at-bat on May 13 against the Mets at Shea Stadium.
Meanwhile, Scott Casto said after Sunday's game that his son, outfielder/infielder Kory Casto, has been playing with a sore oblique muscle in his stomach. It hasn't stopped Casto from playing, however. He hit a game-winning three-run homer against the Mariners on Sunday.
Casto is expected to be the Nationals' primary left-handed bat off the bench, replacing Rob Mackowiak, who was recently given his unconditional release.
"We had a talk in Spring Training, and I told him the worst he could do on this team was to have Mackowiak's job in the future," manager Manny Acta said.
Infielder Aaron Boone's neck injury is a thing of the past. He started for the Nationals on Sunday and went 2-for-5 with a run scored.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.