RB Trey Sermon most likely to return to San Francisco 49ers' depleted backfield

SANTA CLARA, Calif. -- The San Francisco 49ers don't have a clear picture as to who will play running back for them Sunday night, but the pieces started to come together on Friday.

After losing running backs Elijah Mitchell (right shoulder), JaMycal Hasty (left ankle) and Trey Sermon (concussion) in the Week 2 win over the Philadelphia Eagles, it was fair to wonder who, exactly, would play running back against the Green Bay Packers.

While coach Kyle Shanahan immediately ruled out Hasty, who is expected to go on injured reserve, he left the door open for Mitchell and Sermon.

Sermon looks like the best bet to start against Green Bay after Shanahan said he had a good week of practice. Sermon cleared the concussion protocol Friday morning and participated in all three practices during the week. He wore a blue no-contact jersey Wednesday and Thursday but was able to shed that for Friday's workout.

"With the rules of protocol, you can't do everything, but he's been great all week," Shanahan said. "Just what he has been able to do individual [drills] and then getting to do everything today, but you're never fully sure of it until they clear the [protocol]."

Mitchell's situation is more tenuous, as he is listed as doubtful to play. He did not practice Wednesday and Thursday, though he was spotted doing some work on a side field Thursday. On Friday, Mitchell participated on a limited basis, though that is the lightest practice of the week.

Mitchell stepped in as the starter against the Eagles with Hasty as the backup. Sermon was a healthy scratch in Week 1, then suffered the concussion on his first NFL carry after Mitchell and Hasty departed with their injuries in Philadelphia.

But because the 49ers, who lost starting running back Raheem Mostert to a season-ending knee injury in Week 1, are so light on proven options at the position, Shanahan is holding out hope Mitchell will be available in some capacity.

"I think in this situation where you're down a number of guys and the other guys are brand-new guys, that's why when it comes down to the wire. It's like that," Shanahan said. "If Raheem was still here, obviously Hasty was still there, you would definitely just wait a week. But when you're deciding on guys who are just trying to catch up and learning this week, you're a little more patient with that.

"So if he feels like he can go and the doctors say that he can't hurt himself any worse, then that's why we would do it."

Trenton Cannon, who was claimed off waivers from the Baltimore Ravens last week, and Jacques Patrick, who signed with the team off the Cincinnati Bengals' practice squad Tuesday, are the other backs on the active roster.

San Francisco also has veterans Chris Thompson and Kerryon Johnson on the practice squad as potential options if Mitchell is unable to play.