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

McCaffrey is being placed on injured reserve due to a PCL injury he sustained 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 won’t require surgery and he will miss at least six weeks. With just five weeks left in the regular season, McCaffrey would not return this campaign unless San Francisco mounted what appears to be an unlikely playoff run.

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

Last season’s AP NFL Offensive Player of the Year, McCaffrey did not play in his first game this season until Week 10 after he was placed on injured reserve in September due to calf and Achilles injuries. Now, he has a knee injury to come back from whilst leaving San Francisco concerned about their star tailback’s future.

In four games, McCaffrey recorded 348 scrimmage yards and had zero touchdowns.