In a cold, snowy Week 13 matchup between the San Francisco 49ers and Buffalo Bills, star running back Christian McCaffrey left the game due to a knee injury, per Adam Schefter on X.

McCaffrey suffered the injury early in the second quarter after receiving a pitch and immediately going to the ground. Once he got up, McCaffrey jogged gingerly to the sideline and immediately into the blue medical tent. Schefter later reported that McCaffrey would held to the team's locker room.

This was McCaffrey's fourth game back since missing the first nine weeks of the season, though his current status is unknown.

With a lot of football remaining in this matchup at the time of the injury, the 49ers will look to rely on backup running back Jordan Mason to fill McCaffrey's shoes. However, if McCaffrey can somehow return to this game, it'll be interesting to see if head coach Kyle Shanahan will keep him sidelined to stay safe.

49ers RB Christian McCaffrey injures right knee against Bills

San Francisco 49ers running back Christian McCaffrey (23) is tackled by Buffalo Bills cornerback Taron Johnson (7) in the first quarter at Highmark Stadium.
Mark Konezny-Imagn Images

While McCaffrey left the game after going to the ground immediately after receiving a pitch from Brock Purdy, it appeared that McCaffrey hurt his right knee play before, per David J. Chao, aka ProFootballDoc on X.

One play before leaving the game, McCaffrey was brought down by the shoestrings of his cleats, falling directly onto his right knee. Then, on the following play, McCaffrey left the game.

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Now, after missing so much time in this season already, it'll be interesting to see how the 49ers go about handling McCaffrey's usage in the remainder of the season.

As the 49ers continue to be haunted by the injury bug this season, McCaffrey is the most recent victim. With playoff hopes dwindling by the injury, the 49ers are in a weird spot where they can't afford to lose another superstar on their roster if they want to make another deep playoff run— or one at all.

This update couldn't have come at a worse time, as Shanahan and his 49ers are running out of time to remain alive in the postseason hunt.

At halftime, Shanahan updated reporters, telling them that McCaffrey wouldn't return to the game, per Ian Rapoport on X.

Now, down McCaffrey for an unknown period of time, the 49ers have a monumental hole to dig themselves out of if they want to make a playoff run.