Jordan Mason injury update: 49ers RB joins Christian McCaffrey on IR

The San Francisco 49ers lost running back Christian McCaffrey to what appears to be a season-ending knee injury during their 35-10 "Sunday Night Football" loss to the Buffalo Bills. He was placed on IR with a PCL sprain and is expected to miss at least six weeks of action.

However, McCaffrey wasn't the only member of San Francisco's backfield to be hurt in the contest. McCaffrey's backup, Jordan Mason, suffered an ankle injury that is expected to land him on IR along with the All-Pro.

Mason, 25, was a breakout star for the 49ers early in the season. He replaced McCaffrey as the team's bell-cow back and ran for 147 yards and a touchdown in the team's season-opening win against the New York Jets.

Here's what to know about Mason's injury and how it will impact the 49ers' running back depth chart over the final five weeks of the 2024 NFL season.

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Jordan Mason injury update

49ers coach Kyle Shanahan announced during a Monday news conference that Mason suffered a high-ankle sprain during San Francisco's Week 13 loss to Buffalo. It isn't clear exactly when the third-year running back was injured, but he is being placed on IR because of the sprain.

As a result, Mason will be sidelined for at least four games. Just five games remain in the 2024 NFL season, so the earliest that Mason could return would be Week 18.

If the 49ers fail to make the postseason, the team might decide not to bring Mason back at all and let him get healthy for the 2025 NFL season. At present, San Francisco is 5-7 and sitting in last place in the NFC West, two games behind the pole-sitting Seattle Seahawks.

49ers RB depth chart

McCaffrey and Mason aren't the only 49ers running backs on IR. The team also lost Elijah Mitchell, who was expected to be McCaffrey's backup entering training camp, to a season-ending hamstring injury before the campaign began.

As a result, the 49ers have only one healthy running back on their 53-man roster: rookie fourth-round pick Isaac Guerendo. They will likely elevate Patrick Taylor Jr. from the practice squad to help replace McCaffrey and Mason, but those are the only two healthy running backs presently in the team's organization.

With that in mind, the 49ers will likely bring in another running back to provide depth behind the duo.

This article originally appeared on USA TODAY: Jordan Mason injury update: 49ers lose Christian McCaffrey's backup