McFadden hasn't practiced since the injury and still couldn't run Monday.
"That mid-foot sprain is really something," Raiders coach Hue Jackson said. "You have to get back to walking first before you can do anything, so my main thing is to get him out of that walking boot first. That would be huge progress, and I think he's closer to having that happen."
McFadden did not accompany the Raiders on their flight to Southern California following Wednesday's practice. He stayed behind to get treatment, and Jackson remains hopeful he'll get his best offensive weapon back on the field soon.
Raiders kicker Sebastian Janikowski (hamstring) and defensive lineman Richard Seymour and linebacker Rolando McClain are questionable. Seymour returned to practice Wednesday after sitting out the last two days.
For the Chargers, wide receiver Malcom Floyd (hip) is doubtful after not practicing this week. Running back Ryan Mathews (groin), who missed last week's game, is probable after fully participating in practice the previous two days.
The Associated Press contributed to this report.