San Francisco 49ers v Detroit Lions
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Raheem Mostert's 2021 campaign is over before it could really even get off the ground. The 49ers running back announced Tuesday that he will undergo season-ending knee surgery to repair an injury he suffered during San Francisco's Week 1 win over the Detroit Lions. Specifically, Mostert is said to be dealing with chipped cartilage in his knee. 

The initial plan appeared to be for Mostert to go on injured reserve, miss approximately eight weeks and then return to game action. As he stated in his announcement, however, undergoing surgery gives him the best shot at returning to top form. The recovery time for Mostert is roughly six months, according to Tom Pelissero of the NFL Network

"After consulting with multiple doctors and weighing my options, I will be having season-ending knee surgery to repair my knee," Mostert said in a statement. "This gives me, without a doubt in my mind, the best possibility at coming back 110%. I have ALWAYS come back stronger and I will this time too! I have faith in myself, my doctors, my support system, my team, and God. He makes no mistakes!! 

"I'm gutted. This sucks! This is obviously not what I worked so hard for. I wish more than anything I could be out there on the field with my brothers.!!! Thank you for your support in our decision. I'M FAR FROM DONE!" 

Mostert exited Sunday's opener during the 49ers' second offensive possession after totaling 20 yards on two carries. Sixth-round rookie Elijah Mitchell ascended to the featured role with Mostert injured and impressed, rushing for 104 yards and a touchdown. Along with Mitchell, Jamycal Hasty and rookie Trey Sermon -- who was a healthy scratch vs. Detroit -- should be the three backs San Francisco will deploy with Mostert's season coming to an unexpected close.

Is it Trey Lance time? Or will Jimmy G keep the starting job? Download the CBS Sports app and get the latest 49ers news, all from our team of veteran reporters. If you have the CBS Sports app, make sure to set the Niners as your favorite team and get news delivered to your fingertips.