Williams said Zimmerman, who will miss his 41st straight game on Wednesday, took front-toss in the batting cage without any issue, but the team will be careful with the entire rehab process.
"All indications are that he's not going to damage his thumb any more by swinging the bat, but it could be sore," Williams said. "There's vibration that goes into it. He's been out for some time, so we worry about his back and taking too many swings all at once."
Wednesday will be Zimmerman's first time facing live pitching since he injured his thumb sliding back into the base. Williams said the third baseman will also throw from 90 feet again Wednesday, and he expects Zimmerman to make throws to second base during fielding practice.
In terms of Zimmerman's return to games, Williams said the third baseman would likely first come back in a designated-hitter role against an American League opponent before playing in the field. The manager also didn't rule out playing Zimmerman in the outfield once he officially overcomes his injury.
"There may be times where he has to do that," Williams said. "We don't know. But we're covering all the bases, at this point."
Williams said the most important aspect of Zimmerman's rehab is avoiding a relapse, both in terms of his thumb and arthritic right shoulder. Because of that, the manager said the team would have to take a patient approach, meaning there is still no timetable for Zimmerman's return.
"He's going to have to take it slow and build up to where he just can go out there and throw 40 balls across the infield and have no problem," Williams said. "You can't do it right out of the gate, though, or anybody would get sore. That's part of the process."
Daniel Popper is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.