Raiders coach Tom Cable adopted a wait-and-see approach to naming the starting running back for Sunday's game against the St. Louis Rams.
Expected starter Michael Bush suffered a thumb injury and missed Oakland's first game, a 38-13 loss in Tennessee.
"We're hopeful, but as of right now, we don't know anything," Cable told reporters in St. Louis early Wednesday afternoon.
Darren McFadden started in his place and gained 95 yards on 18 carries. He also caught nine passes for 55 yards. If both are healthy, the Rams will have to prepare for complementary running styles.