Christian McCaffrey’s 2024 season started late and appears to be ending early.

McCaffrey will be placed on injured reserve due to a PCL injury he suffered in the San Francisco 49ers’ 35-10 loss to the Buffalo Bills on Sunday night, head coach Kyle Shanahan announced Monday.

Shanahan added that McCaffrey’s injury does not require surgery and he will be out for at least six weeks. With only five weeks left in the regular season, McCaffrey would not return this season unless San Francisco embarked on a seemingly improbable playoff run.

Additionally, backup running back Jordan Mason joins McCaffrey, who is injured with an ankle sprain, on the bench, Shanahan added. Isaac Guerendo is expected to be San Francisco’s lead back for the remainder of the 2024 season.

McCaffrey, last season’s AP NFL Offensive Player of the Year, didn’t play his first game this season until Week 10 after being placed on injured reserve in September due to calf and Achilles tendon injuries. Now he must recover from a knee injury while leaving San Francisco and worrying about the future of his star tailback.

In four games, McCaffrey recorded 348 scrimmage yards and did not have a touchdown.