49ers' Elijah Mitchell out 6-8 weeks with MCL sprain
Mitchell suffered the injury in the 49ers' win against the New Orleans Saints on Sunday. He left the game in the third quarter and didn't return.
"He's pretty disappointed," Shanahan said, according to David Lombardi of The Athletic.
Shanahan added, "He's had really bad luck. ... Hopefully, we can do our job here so when he comes back, we're still playing."
Mitchell suffered an MCL sprain in Week 1 against the Chicago Bears. He missed the next seven games. Sunday's contest was just his fourth of the season.