Zimmerman is scheduled to play in another simulated game on Friday and at that time, it will be determined when he will be able to return to active duty.
Zimmerman has not played since July 22 after suffering a Grade 3 hamstring strain.
"He had a full workout. He hit in the cage, he did a full day's work," Nationals manager Matt Williams said, according to MLB.com. "He said he felt great afterward, so we'll push him to five innings [Wednesday] and see where he is at after that."
Williams said that Zimmerman will play leftfield, third base and first base when he returns from the disabled list.
Zimmerman is hitting .282 with five home runs and 36 RBI in 53 games this season for Washington, which clinched the National League East on Tuesday with a win over Atlanta.
- Scooby Axson