Niners place Christian McCaffrey (calf/Achilles tendon) on the injured list; running back will miss at least four games

McCaffrey missed most of training camp and did not play in the preseason because of a calf strain that head coach Kyle Shanahan announced on August 6.

The threat seemed small, however, as Shanahan said a few weeks later that he wasn't concerned about McCaffrey's readiness while he dealt with the injury. Bigger problems seemed to be looming, namely the loss of left tackle Trent Williams and wide receiver Brandon Aiyuk due to contract disputes.

But those stalemates both ended before Week 1, and Williams and Aiyuk appeared in the team’s 32-19 victory over the New York Jets on Monday Night Football.

McCaffrey, surprisingly, did not do so and will not do so for quite some time.

Jordan Mason served as San Francisco's RB1 in his place, rushing for 152 yards and a touchdown on 29 touches. It was a great prime-time performance that bodes well for the 49ers having to endure a period without their most dangerous weapon, but there's still no replacement for all that the versatile McCaffrey, a two-time All-Pro and one of the NFL's best pass-catchers, has to offer.

Deebo Samuel will likely need to spend more time in the backfield than he did on Monday to fill the receiver void there, and more backups like Isaac Guerendo and Patrick Taylor (three offensive snaps combined in Week 1) will need to be used to keep Mason fresh in what could be his new workhorse role.

The 49ers play the Minnesota Vikings, Los Angeles Rams, New England Patriots and Arizona Cardinals over the next four games. If CMC spends as little time as possible on the injured list, he could return on October 10 for a Thursday night showdown against the Seattle Seahawks.

San Francisco's two games between that contest and a Week 9 off are at home against the Kansas City Chiefs and Dallas Cowboys.