Littell (oblique) will begin a rehab assignment at Single-A San Jose on Friday, Susan Slusser of the San Francisco Chronicle reports.
Littell has been on the injured list since early July due to his left oblique strain but is closing in on a return. It's not yet clear how many rehab appearances the right-hander will require before he's able to rejoin the Giants' bullpen, but it's possible that he'll be activated as early as next week.