An MRI of Ryan Zimmerman's right shoulder confirmed the Nationals' initial diagnosis of inflammation to the AC joint, not a serious injury, but the third baseman may still need a brief stint on the disabled list.
Zimmerman told reporters in San Diego this afternoon he'll attempt to take batting practice before tomorrow's series finale at Petco Park. If that doesn't go well, he would likely need to receive a second cortisone shot (following one he received Saturday in Washington) and then be placed on the 15-day DL.
Any DL move would be retroactive to Saturday, because Zimmerman has not played since then, so he would be eligible to return as soon as May 6 (the Sunday night finale of the Nationals' home series against the Phillies).
Zimmerman's absence for any length of time would be a serious blow to a Nationals lineup that is already struggling to score runs without cleanup hitter Michael Morse (who won't be cleared to resume baseball activities for at least another month due to a strained lat muscle). Though they own the NL's best record entering play today at 13-4, they've scored a total of only 12 runs in their last five victories, managing to squeak by thanks to the league's best pitching staff so far this season.
Manager Davey Johnson said he'll mix and match players at third base in Zimmerman's absence. Rookie Steve Lombardozzi started last night, but veteran Chad Tracy will be in the lineup for tonight's game against the Padres.
If Zimmerman lands on the DL, possible candidates to fill his roster spot include outfielder Brett Carroll (who was designated for assignment April 14 but has now reported to Class AAA) and first baseman Tyler Moore (who has already hit six homers in 17 games for Syracuse).