With running backs Darren McFadden and Mike Goodson likely out with high-ankle sprains, rookie Taiwan Jones may get a chance to shine Sunday against Baltimore. (US Presswire)

Starting RB Darren McFadden and backup Mike Goodson missed practice for the second straight day Thursday with high-ankle sprains and, according to coach Dennis Allen, were in walking boots.

Allen hasn't officially ruled out either player for Sunday's game against Baltimore, but all signs point in that direction.

"They didn't practice today, but I won't make any decision until after practice on Friday," Allen said.

Marcel Reece, who started the first eight games at fullback, and No. 3 running back Taiwan Jones, took the first-team reps at running back during practice, Allen said.

Reece signed with the Raiders in 2008 as an undrafted rookie out of Washington, where he played wide receiver. Raiders offensive coordinator Greg Knapp was in the second season of his first stint in Oakland that year.

"We didn't know where to put him, so we moved him around a little bit and played him at back a little bit, then we had him at tight end, had him play a little receiver," Knapp said. "We studied him coming out of college and he'd carried a little bit so I have a familiarity with him and his background, although he hasn't done as much in the NFL.

"But I have complete confidence, and he had to play last week, a quarter and a half, at the one-back spot for us and did a fine job. So I'm very confident. He doesn't have the intangibles of a Darren McFadden, but he does bring some good qualities in his own right to carry the ball."

Jones, the fastest player on the team, has speed but has rarely carried the ball since being drafted in the fourth round last year out of Eastern Washington. He's been slowed by hamstring and knee injuries and, according to Knapp, has been held back by "ball security"  and "assignment" issues.

"Some of the assignment issues have been because of lack of reps because of the injuries," Knapp said. "So you miss out on opportunities due to lack of reps. I'm excited for the young kid. I hope he gets a chance to get out there and have some confidence and have some successful plays to build his confidence because he's flashed at times. He can make some plays, but we're looking for more consistency and hopefully he's had a chance to get some good reps this week and it will carry over to the game if he ends up being used in the backfield."

Practice squad RB Jeremy Stewart, a rookie from Stanford, has been getting some reps in practice with the regular offense and on some front-line special teams units. If McFadden and Goodson are out Sunday, it's likely that Stewart will be promoted to the 53-man roster and play against Baltimore.

"They basically told me to be ready, and we'll see what happens," Stewart said. "You have to approach every day like you're going to be the guy starting. Since I've gotten here I've been preparing for my opportunity. So if it presents itself this weekend, I'll be ready."

Stewart carried just 55 times for 257 yards last season for Stanford, but he scored nine touchdowns.

"I feel like I'm a good finisher," Stewart said. "I can find the end zone."

Follow Raiders reporter Eric Gilmore on Twitter @CBSRaiders.