CINCINNATI - Ken Griffey Jr. had surgery Monday to repair his torn right hamstring and is expected to return for spring training, the Cincinnati Reds said.

''I am very optimistic for a complete return to normal activity,'' said Dr. Timothy Kremchek, the Reds' medical director who did the two-hour operation.

Griffey, 34, begins four months of rehabilitation Thursday. He will remain in a sling harness four to six weeks.

Kremchek attached Griffey's tendon to the bone with three screws and cleaned up scar tissue, the Reds said.

Kremchek said last week that an MRI indicated Griffey had ruptured his hamstring the week before in San Francisco. It was the latest in a long line of injuries for the Reds' center fielder.