To take his place on the roster, the Nationals recalled infielder Zach Walters from Triple-A Syracuse. He was available for Wednesday's game against the Colorado Rockies.
Zimmerman was injured in the sixth inning Tuesday night while running out a grounder. Manager Matt Williams says Zimmerman had an MRI on Wednesday and remains ''pretty sore.''
The 29-year-old Zimmerman missed 44 games with a fractured right thumb earlier this season.
The Nationals are 33-19 this year when Zimmerman is in the lineup. He's hitting .282 with five homers and 36 RBIs.