Chargers RB Ryan Mathews (clavicle) and OLT Jared Gaither (back) will miss Monday night's game at Oakland, the club said Saturday.
Both players are now listed as "out" on the club's injury report after not practicing Saturday.
Veteran Ronnie Brown is likely to start in place of Mathews, while rookie Mike Harris, an undrafted free agent from UCLA, will start for Gaither.
In other Chargers injury news, DT Antonio Garay (ankle) is listed as questionable for Monday's game. He practiced on a limited basis Saturday.