Okung injured his groin on Philip Rivers‘ interception on the first drive.
Although the Chargers listed him as questionable to return and have not updated since status since, Okung has not returned.
Trent Scott started for Tevi, who played only 14 snaps Sunday before injuring his knee and is inactive tonight.
The Chargers replaced Okung with rookie Trey Pipkins.
A third-round choice, Pipkins had played only nine offensive snaps before replacing Okung.
Ferrell briefly left for the locker room in the third quarter.
Chargers defensive end Melvin Ingram also briefly left. The team announced a shoulder injury, but he re-entered the game, too.
The Raiders lead the Chargers 20-17 at the start of the fourth quarter.