"He's being described as 50-50," Cubs general manager Jed Hoyer said of LaHair. "He's optimistic. He's only going to play if he can help us. It's not easy to hit [Stephen] Strasburg if you're not close to ready."
Strasburg will be starting for the Nationals on Thursday, when the Cubs kick off the season at Wrigley Field.
LaHair has not played since last Friday because of tightness in his back. If he does not start, Cubs manager Dale Sveum said either Blake DeWitt, Jeff Baker or Joe Mather will start at first. The Cubs' Opening Day lineup was not finalized until Sveum knows if LaHair can go.
The plan Thursday is for LaHair to get treatment, hit off a batting tee and then the medical staff will make an evaluation.
"If it goes really well, we'll probably let him hit, and if that goes really well, probably get him in the lineup," Sveum said.
LaHair, 29, who led the Pacific Coast League with 38 home runs last season at Triple-A Iowa, has made the Opening Day roster for the first time in his pro career.