Coach Dennis Allen plans to use both against the Cowboys.
"The guy that's in there and being the most effective will be the guy that gets the opportunity," Allen said. "But I see them both getting a chance to carry the ball. We'll see how it goes. We'll play it out as the game plays along."
McFadden said he is still sore from the hamstring injury — his second this season — and added that he needed the extra time off as a precaution.
"To me, I could have been back last week but I just have to take my time with it," he said. "I don't want to. I know if I rush it back again this time it will probably be over for the season. So I want to just be able to make sure it's all the way back right before I get out there again."
Even if he remains healthy the remainder of the season with Oakland, it's questionable whether the 26-year-old running back will be invited back next season.