Christian McCaffrey's hugely frustrating 2024 season is over.

Despite some optimism expressed by the San Francisco 49ers running back's father earlier on Monday, the reigning Offensive Player of the Year will head to injured reserve after suffering a PCL injury in his right knee during Sunday's loss to the Buffalo Bills.

Speaking in his Monday conference call with local media, Shanahan said the injury requires a six-week recovery. The 49ers have only five games of the season remaining after dropping to 5-7.

McCaffrey looked to have regained the explosiveness that had been lacking in previous weeks following his return from bilateral Achilles tendinitis in the first half against Buffalo. However, a cruel twist of fate ended his campaign as he damaged his knee on a shoestring tackle from Taylor Rapp that prevented a potential touchdown run.

The bright side for McCaffrey is that he does not need surgery and, after a year dominated by injuries, he will now get the chance for an elongated rest in order to be ready for 2025.

San Francisco will also be without Jordan Mason, who thrived in McCaffrey's initial absence, for the remainder of the year because of a high ankle sprain. Mason's 78 yards against Buffalo took him to 789 for the season, but he will not get the chance to reach 1,000. 

Instead, the 49er backfield will now be led by fourth-round rookie Isaac Guerendo, who scored his second career touchdown against Buffalo.

Defensive tackle Kevin Givens is also done for 2024 because of a torn pectoral that will send him to injured reserve.

Trent Williams (ankle) and Nick Bosa (hip/oblique) will both be re-evaluated this week after missing the last two games. Williams is, understandably, still the processing the loss of baby twins, Shanahan said when asked about his All-Pro left tackle's family tragedy.

Deommodore Lenoir is set to practice on Wednesday having missed the Buffalo game with a knee injury while linebacker Demetrius Flanningan-Fowles, also dealing with a knee problem, is day-to-day.

Left guard Aaron Banks and defensive tackle Jordan Elliott remain in the concussion protocol, but there was a positive update on safety Talanoa Hufanga (wrist), who is set to have his practice window opened.

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