The 49ers are now considering placing Christian McCaffrey on injured reserve, which would sideline him this week plus three more games, Shanahan said.

Related Players: Jordan Mason, Isaac Guerendo, Patrick Taylor

While it's possible that the team brings in another back, they sure weren't opposed to giving Jordan Mason a phenomenal workload last Monday. As it stands, Mason is a must-rostered, must-start option for as long as McCaffrey is out.

49ers RB Christian McCaffrey (Achilles/calf) feels like a long-shot for Sunday against the Vikings.

Related Players: Jordan Mason, Isaac Guerendo

Jordan Mason went nuclear as a last-minute start in Week 1, so he should be in fantasy lineups of McCaffrey misses again. Guerendo and even Patrick Taylor could be rotated in a little more in Week 2, but aren't worth fantasy stashes quite yet.

The 49ers will have wide receiver Brandon Aiyuk and left tackle Trent Williams against the Jets on Monday night, but they will not have running back Christian McCaffrey.

Jordan Mason, Patrick Taylor and Isaac Guerendo are the available backs for the Niners.

Definitely a shocker and likely a big blow to fantasy owners. According to the story, McCaffrey said on Friday that he had no doubt he would play and there was plenty of optimism from head coach Kyle Shanahan and General Manager John Lynch as well. McCaffrey missed most of the summer with a calf injury and is listed with an Achilles issue as well, the story said. Mason had a great camp and seemed to get a lot of attention from coaches this summer, and likely should get a bulk of the workload tonight against the Jets. Hopefully CMC owners backed themselves up during drafts by nabbing Mason. If Mason is still on your wire, he's worth picking up for any team in case CMC's issues are longer term. Taylor and Guerendo could get work for the Niners as well - if you're in a pinch losing CMC. From the Jets side, Braelon Allen and Israel Abanikanda could see touches behind Breece Hall.

Running back Elijah Mitchell went on season-ending injured reserve.

Related players: Christian McCaffrey, Jordan Mason, Isaac Guerendo, Matt Breida

Mitchell can only play this season if the 49ers reach an injury settlement with him and waive him from injured reserve, the story said. Mitchell has struggled to stay on the field but when he has played he's certainly impressed. Mason has had a good camp, according to reports and the team has praised his running style so he'll backup CMC. The team traded up to draft Guerendo, so there's a good chance he has a role this season as well.

"Nothing against Elijah Mitchell, but Jordan Mason runs at a very high level." - 49ers HC Kyle Shanahan on Mason earning reps at RB2 when Christian McCaffrey isn't in.

Related players: Isaac Guerendo

Guerendo is going to miss some time at camp and with the rookie out of action, it could mean the RB2 role ends up going to Mitchell or Mason. Mitchell struggles to stay healthy at times, but has excelled in the starting role before. It could just be coach-speak about Mason, but it's also worth paying attention to, especially if you're looking to handcuff McCaffrey this season.

WR Jacob Cowing (hamstring) will likely be out approx 10 days total

RB Isaac Guerendo (hamstring) will be out several weeks.

Related players: Elijah Mitchell, Ricky Pearsall, Jauan Jennings, Jordan Mason

It's always tough for rookies when they miss time in camp. Guerendo was said to be battling for the RB2 spot with the often-injured Mitchell. The Niners traded up to get Guerendo who was having a nice spring. Meanwhile at WR, the team got back Pearsall today but Cowing was trying to work his up with the depth chart as well.

Reigning Offensive Player of the Year Christian McCaffrey once again has reset the RB market, signing a two-year extension with the 49ers, averaging $19 million per year.

McCaffrey will receive an additional $8 million over what he was scheduled to make in the first two years while adding $24 million in guarantees.

Related Players: Elijah Mitchell, Isaac Guerendo, Cody Schrader

McCaffrey solidifies himself on one of the best offenses in the league, and should still be viewed as the best RB option in fantasy football.