Samuel (shoulder) is listed as questionable ahead of Sunday's game against the Raiders, Kris Rhim of ESPN.com reports.

Head coach Jim Harbaugh told reporters that Samuel tweaked his shoulder during Friday's practice and is now in jeopardy of missing the Chargers' regular-season opener Sunday, per Rhim. If Samuel is unable to suit up in Week 1, expect Kristian Fulton, Deane Leonard and Cam Hart to see increased snaps at outside corner.