ALAMEDA -- The fact that Darren McFadden has been here before doesn't make it any easier.

The Raiders officially listed McFadden as doubtful Friday with a hamstring strain, meaning it's likely he will miss the 24th game of his career due to injury.

Only on rare occasions does player listed as doubtful on Friday end up playing on Sunday, which also means center Stefen Wisniewski, who has the same designation, could end up a spectator when the Raiders host the San Diego Chargers Sunday night.

``I can't even describe it or put it into words,'' McFadden said when asked about his level of frustration with being injured again. ``I just try to keep my head up, keep pushing forward an remain positive.''

McFadden acknowleged the possibility of sitting out back-to-back games against San Diego and Kansas City preceding the bye week would ``help me out a whole lot'' but stressed he was taking it ``day to day.'' He has yet to be able to sprint.

``Hamstrings are one of those things you want to be careful with,'' McFadden said. ``I'd rather miss one or two games than to come back and pop it and miss four or five.''

Allen said Wisniewski's progress hasn't been what the Raiders hoped but didn't rule him out of recovering before Sunday night.

If Wisniewski can't play, left guard Andre Gurode would start at center. Complicating matters is that guard Lucas Nix (ankle) and starting right tackle Tony Pashos (groin) are both listed as questionable. So is tackle Menelik Watson, just coming off arthroscopic knee surgery.

In an extreme circumstance, players such as guard Antoine McClain, guard Lamar Mady and practice squad tackle James Cornell could be forced into action.

``It's been hard,'' Gurode said. ``You've just got to make sure everybody is communicating on the same page and you go out and play an do the best you can.''

For more on the Raiders, visit the Inside the Oakland Raiders blog at ibabuzz.com/oaklandraiders. Follow Jerry McDonald on Twitter at twitter.com/Jerrymcd.