MILWAUKEE -- After receiving a second reading of an MRI on his left knee, Pirates outfielder Brandon Moss will undergo surgery to remedy a problem that is causing bits of cartilage to separate from the bone near the knee joint.

Moss visited Dr. Richard Steadman in Vail, Colo., on Thursday, and Steadman, like Dr. Patrick DeMeo in Pittsburgh had on Monday, recommended that Moss undergo the microfracture procedure. The other option would have been to continue monitoring the problem to see if it worsened over time.

Steadman will perform the procedure next Friday. In the meantime, Moss will go back to Pittsburgh to pack up his stuff and return it to his home in Atlanta.

Because the problem was found early enough, the extent of the damage to the bone is not believed to be too significant. As a result, general manager Neal Huntington said that the organization is optimistic that Moss could be rehabbed and ready to go at the start of the 2009 season.

"At this point in time, we're still optimistic that he will make a full recovery and be on the field at some point early next spring," Huntington said.

The typical recovery period after such a procedure is eight weeks of rest followed by four to six months of rehabilitation.

Before leaving the club on Tuesday, Moss spoke about being optimistic that he would not require the surgery. He underwent the MRI simply as part of an end-of-the-year medical exam and insisted that he had felt no discomfort in his knee since June.

"Obviously, they're doctors, and they know more about my body than I do," Moss said on Tuesday. "But I know how it feels. It doesn't bother me. I'm playing at 100 percent."