Zimmerman hit a go-ahead, two-run homer as a pinch-hitter Thursday in Philadelphia, but he said Friday before the Nationals played Milwaukee he's not quite ready to return.
"I'm getting closer and closer every day," Zimmerman said. "It feels better every day."
Zimmerman hurt his hamstring on April 10. In the six games he's played, he's batting .250 with the home run and four RBIs.
"The biggest thing is I don't want to go all this time and come back one or two days early and have to start over again," he said.
Except for a left shoulder injury that limited him to 106 games in 2008, Zimmerman's career has been relatively injury-free. He sat out just five games in 2009.
Zimmerman can pinch hit, but his running is still restricted. Manager Jim Riggleman said he would discourage him from trying to beat out a groundball.
"I have to make sure when I put him in there he doesn't have an injury related to this," Riggleman said. "We have to make sure he's 100 percent before I put him back in there."
Zimmerman joked that he felt healthy when trotting around the bases after the home run in the eighth inning against the Phillies.
"I could have had a broken leg [Thursday] and I would have been all right," he said.