Raiders starting running back Darren McFadden and backup Mike Goodson missed practice Wednesday, three days after suffering high-ankle sprains against Tampa Bay.

MRI's on both McFadden and Goodson were negative, Raiders coach Dennis Allen said. But Goodson had a walking boot on his right foot, and high-ankle sprains often linger for weeks.

"I'm not going to make any decision on whether they're playing until Friday after practice," Allen said. "We'll see how the week plays out. Obviously we've got a plan in place if either or both of those guys are not able to play."

The Raiders haven't signed a free agent roster to strengthen their depleted running back corps. Allen was asked if that's a sign that McFadden and Goodson may be close to returning.

"I think it's a reflection that we feel like we've got some guys in-house that we feel like could step in if need be," Allen said. "That's the way it is anywhere in the NFL. It's really a next-man-up philosophy, and we're going to have to count on some guys to step up potentially and fill a bigger role. We'll know more at the end of the week ... exactly what we've got to do."

If neither McFadden nor Goodson can play this week at Baltimore, Oakland's options at running back will be limited.

Taiwan Jones, arguably the fastest Raider, is the only other running back on the roster. He has one carry for 2 yards this season and fumbled on the play. Last year, as a rookie, he carried 16 times for 73 yards.

Marcel Reece took some practice reps at running back during training camp when McFadden, Goodson and Jones were all injured but never got a carry in an exhibition game. During the regular-season opener against San Diego, Reece got the ball once on a running play, but he made a bad pitch to Jones on an aborted reverse and was charged with a fumble.

After McFadden and Goodson were injured against Tampa Bay,  Jones and Reece took snaps at running back, but neither carried the ball.

Jeremy Stewart, a rookie from Stanford, could potentially be promoted from the practice squad, Allen said.

Carson Palmer said he "can't wait" to see what Jones can do in a game.

"He does amazing things in practice, and he's by far the fastest person on the field, and he will be the fastest person on the field Sunday," Palmer said. "And not that you want to see guys get banged up, but I'm excited about the opportunity he's getting.

"I feel like since I've been here, I've waited for him to get this opportunity and it hasn't worked out and here it is. He'll get his touches, and I can't wait. I mean, he's so electrifying. He puts his foot in the ground and goes. He wiggles out of hits, he wiggles out of tackles. Can't wait to throw him the ball, get him in the open field."

The Raiders drafted Jones in the fourth round last year out of Eastern Washington. In his first two seasons, he has been slowed by hamstring and knee injuries. This week, he's not on the injury report.

"I’m definitely excited," Jones said. "There’s definitely an opportunity for me to extend my role on the team. I’m getting the opportunity so I want to make the most of it."

Allen said Jones has been "a little up and down" this season. "A little injury-prone, or injury-plagued, and so it's been kind of tough to evaluate because he's missed some time. But we got confidence in Taiwan, and if he's called on to step in and play, then we fully anticipate him stepping in to perform and do his job."

Can Jones be an every-down back?

"I think that remains to be seen," Allen said. "If he's called on to do that, then that's when we'll know."

Follow Raiders reporter Eric Gilmore on Twitter @CBSRaiders.