Green is managing a neck injury and is considered day-to-day, Nick Wagoner of ESPN.com reports.
Green presumably picked up the issue during Sunday's Week 3 win over Arizona, during which he logged 57 of San Francisco's 66 defensive snaps and finished with four tackles. The cornerback's practice participation level this week should provide more insight about his likelihood of suiting up Sunday versus Jacksonville. If Green can't play in that game, Darrell Luter could be in line for a larger role.