San Francisco 49ers starting RB Elijah Mitchell suffers injury to knee

For the second year in a row, the 49ers starting running back left the opener with a knee injury.

Just before halftime, the Niners starter left the game with a knee injury.

It wasn't immediately clear how Mitchell got hurt, though his last snap before the injury was a touchdown by Samuel. A Bears defender rolled into the back of his legs as Mitchell was blocking for Samuel.

Mitchell carried the ball for 41 yards before leaving. Mitchell was out of the preseason due to a hamstring injury.

Jeff Wilson Jr. took Mitchell's place as the primary running back. The third-round pick out of LSU is on the 53-man roster.

It was almost a year ago that Niners starting running back Raheem Mostert left the opener with a knee injury. The Miami Dolphins signed Mostert in the off-season.