Getty Images

Elijah MitchellHis knee injury was more serious than expected, and the 49ers running back will miss 6-8 weeks.

“He. She It wasn’t news 49ers head coach Kyle Shanahan said on a conference call with local media, via Jerry McDonald of East Bay Times.

The team initially thought Mitchell had a sprained MCL that would keep him out for 2-4 weeks.

“It’s very frustrating,” Shanahan said. “Everyone knows how good Elijah is, how hard he’s worked to come back from last time, how good he’s played since coming back. To come back out there, I know he was real about it. He had some bad luck. He got dumped and it was a bad situation for him.”

Mitchell, who set a rookie record with 963 yards last season, only returned from injured reserve on November 12. He injured his knee in the season opener and missed seven games.

Mitchell had 34 carries for 183 yards in the past three games while splitting time with her Christian McCaffrey Like the 49ers’ running back. McCaffrey exited Sunday’s game with “a sore knee,” so the 49ers will be watching him this week as they prepare to host the Dolphins.

rookies Jordan Mason And Tye Davis-Price could see more playing time this week. Mason had five catches for 25 yards on Sunday against the Saints.