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.