San Francisco 49ers running back Raheem Mostert will miss the rest of the 2021 campaign after electing to undergo season-ending knee surgery.
Mostert was injured in the first half of the 49ers' season-opening 41-33 win over the Detroit Lions on Sunday.
Head coach Kyle Shanahan had indicated Mostert would be out for eight weeks with chipped knee cartilage.
However, Mostert has elected to go down the route of protecting the long-term health of his knee by having an operation to repair the cartilage.
In a statement posted on Twitter, Mostert wrote: "After consulting with multiple doctors and weighing my options, I will be having season-ending surgery on my knee.
"This gives me, without a doubt in my mind, the best possibility at coming back 110 per cent.
"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!!"
Mostert was the starting running back for a 49ers team looking to get back to the postseason after seeing their 2020 season ruined by injuries. The last time they made the playoffs in the 2019 campaign, Mostert propelled them to Super Bowl LIV by rushing for 248 yards and four touchdowns in an NFC Championship Game rout of the Green Bay Packers.
He became the first player to rush for at least 200 yards and four touchdowns in a playoff game, while his 248 yards represented a record for a conference title game.
Yet the 49ers have sufficient if inexperienced running back depth to survive Mostert's absence, as evidenced by the performance of sixth-round rookie Elijah Mitchell, who rushed for 104 yards and a touchdown against the Lions.
Mitchell, JaMycal Hasty and rookie third-round pick Trey Sermon will now share the load in the backfield. The Niners, who also lost cornerback Jason Verrett to a torn anterior cruciate ligament against Detroit, signed former Lions tailback Kerryon Johnson to their practice squad.