Manager Manny Acta didn't give a timetable as to when Olsen would return to action.
Meanwhile, catcher Jesus Flores is going on a rehab assignment with Double-A Harrisburg. Acta hopes to have Flores back with the Nationals for next weekend's series against the Phillies in Philadelphia.
With Flores coming back, the Nationals have to choose between fellow catchers Josh Bard and Wil Nieves. Bard has made dramatic improvements on defense and is largely credited for helping the young pitchers, such as Craig Stammen and Ross Detwiler.
Nieves is out of options and appears less likely to go. He has done the job on offense and defense. Entering Sunday's action, Nieves is hitting .265 with four RBIs.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.Less