San Francisco 49ers running back Elijah Mitchell will be sidelined for eight weeks with a knee injury, according to head coach Kyle Shanahan.

Mitchell sprained the MCL in his right knee in Sunday's 19-10 loss to the Chicago Bears, exiting the game in the second quarter.

The 24-year-old running back, who scored seven touchdowns across the 2021 season, had six carries for 41 yards in the game before being ruled out at half-time.

"We're estimating about two months, eight weeks, give or take a few," Shanahan said. "Hopefully, it goes well and it's earlier but you never know with those things, so that's what we're guessing."

Mitchell broke the 49ers' single-season rookie rushing record in 2021, rushing for 963 yards in 11 regular-season games, along with a further 169 yards in the postseason.

"He was pretty down," Shanahan said. "For obvious reasons, we're down for him. Elijah went through a lot last year, it's well documented the injuries he had.

"He really worked hard this offseason. He was feeling really good going into that game and I thought he looked really good before he got hurt.

"And just unfortunate hit that he had. I just tried to tell him to keep his head up. Anybody who would have gotten caught in that situation would have gotten hurt with the way his foot planted in the ground and the guy hit his knee. I think we were just real fortunate it wasn't worse."