Manager Jim Riggleman said that Zimmerman was feeling uncomfortable when it came to throwing the baseball, but he is still going to play third base in the game.
No timetable was announced as to when Zimmerman will start his a rehab assignment, but he is expected to play in a big league game in mid-June.
Zimmerman's absence is one of the reasons the Nationals are ranked near the bottom of the Majors in offense. But unless they can make a trade involving catcher Ivan Rodriguez and/or reliever Todd Coffey, the Nationals aren't expected to make any changes before Zimmerman returns.
The team doesn't have anyone in Double- or Triple-A who could make an impact offensively right now. It was already reported that first baseman Chris Marrero was not on the radar to get a promotion to the big leagues. He has started hitting in the last couple of weeks, but he most likely will not be in the big leagues until September.
Asked if he had problems putting together a lineup, Riggleman said, "I really see our offense coming together. I think in the last couple of weeks, you see what Mike Morse and Laynce Nix have done. ... You see what Danny Espinosa has done.
"We have a few guys who have yet to get it going offensively, but I feel like we are going to get it together as a team offensively. In the meantime, we have to win ballgames in some manner."