Sources: 49ers WR Brandon Aiyuk suffered a season-ending knee injury on Sunday, tests confirmed.

Related players: Deebo Samuel, Jauan Jennings, Ricky Pearsall, Chris Conley, Ronnie Bell, Jacob Cowing, Trent Taylor, George Kittle, Christian McCaffrey

Anyone who held on to Jennings should be in good shape as he will likely slide in as the team's WR2 behind Deebo. Jennings didn't play in Week 7 because of a hip injury but the team is hoping to have in back for Week 8, according to reports. Pearsall was active for the first time and caught three balls for 21 yards. Cowing had two catches for 50 yards. Both rookies could be options behind Samuel, Kittle and likely Jennings, but may not be consistent fantasy producers. We reported McCaffrey is looking to return on Nov. 10 and it's possible he's counted on as a receiver more than a rusher once he's back.

49ers RB Christian McCaffrey's target to return is early November. The Niners have a bye the first week of November, but November 10 could be a potential return date, according to Ian Rapoport.

Related players: Jordan Mason

Rapoport said CMC continues to ramp up. He's been running on flat ground and there is no reason to be pessimistic, and it's been all systems go up to this point, Rapoport said. It's good news for McCaffrey and a potential return. As far as fantasy goes, hopefully his owners are still alive for a playoff berth by the time we get to Nov. 10. It may not be fair to think CMC jumps right into his normal bell cow role his first game back. The team may opt to continue to use Mason, who has done a great job filling in. With the potential loss of Brandon Aiyuk, CMC owners shouldn't have much worry inserting him in lineups once he's back.

San Francisco 49ers star running back Christian McCaffrey has bilateral Achilles tendinitis, meaning he has it in both legs, per NBC Sports. McCaffrey recently went to Germany for treatment.

The 49ers said they expected to get a "better idea" on McCaffrey's status over the next few weeks. The team's plan was to ramp up his rehabilitation to "see how it responds." General manager John Lynch added that the team is aiming to "quiet down" the injury.

Related players: Jordan Mason, Isaac Guerendo, Patrick Taylor

The story said Achilles tendinitis is described as "an overuse injury of the Achilles tendon, the band of tissue that connects calf muscles at the back of the lower leg to your heel bone," according to the Mayo Clinic. Some Achilles tendinitis can be treated at home, while more serious cases can lead to tendon tears that may require surgery. The story went on to say, until McCaffrey, the team and the medical specialists see how the area responds to more work, it's hard to make a call on when he will be back, if he does come back this season. NFL Media reported Sunday that McCaffrey should be back, at least, by early November, but the report of bilateral Achilles tendinitis could change things. For now, Mason remains the bellcow. He had 24 carries in Week 4 with Deebo Samuel getting two. Guerendo had a fumble on special teams and had just one carry in the game.

And to top it off, 49ers RB Christian McCaffrey is seeing a specialist in Germany regarding his Achilles tendinitis.

Related players: Jordan Mason, Isaac Guerendo, Patrick Taylor

This doesn't sound good for CMC. Now owners can't help but wonder if McCaffrey will be back after missing his four games on IR. Mason has filled in well, gaining 5.2 yards per attempt with two touchdowns on the season. But at this point, with CMC seemingly a huge question mark, it may be time to pick up players like Guerendo and Taylor. Guerendo was the only other back to get carries in Week 3, running five times for 19 yards.

The 49ers are placing RB Christian McCaffrey (calf/Achilles) on injured reserve, per Adam Schefter of ESPN.

The 49ers had been leaning in this direction. They will now be without CMC for at least the next four weeks, meaning he will miss games against the Vikings, Rams, Patriots and Cardinals. He'll probably also miss a fifth game, as the 49ers have a short week after the Cardinals game before a Thursday night game in Week 6 against the Seahawks. Perhaps he can return for the Super Bowl LVIII rematch in Week 7 against the Chiefs. For now, it will be the Jordan Mason Show after his huge Week 1 performance against the Jets -- 28 carries, 147 yards.

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.

San Francisco 49ers head coach Kyle Shanahan pushed back at an earlier ESPN report that star running back Christian McCaffrey could miss Week 2.

When Shanahan was asked about the report from Adam Schefter after the 49ers' 32-19 win on Monday night over the Jets, Shanahan had a quip ready to go.

"That person must've been God," Shanahan said. He added that McCaffrey was a gametime decision on Monday night.

Related players: Jordan Mason

Schefter said McCaffrey pulled out of practice on Friday and no one was overly concerned at the time. But the calf was still tight on Monday before the game when he came in for treatment. However, it's not just his calf, he's also dealing with an Achilles issue. The team made the decision to play it safe since it's a long season and make CMC inactive, Schefter said. Schefter added it's a "strong possibility" McCaffrey won't play in Week 2, at Minnesota on turf. Mason had a huge game taking over for CMC on Monday night against the Jets. It's not necessarily a surprise as the team talked up Mason most of the summer. This is obviously worth monitoring and we can probably expect many different updates for the rest of the week leading up to Week 2. Mason should again be a nice play if CMC can't go. The Niners-Vikings game is also an early game on Sunday so owners will have time to adjust.

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.

49ers RB Christian McCaffrey is listed as questionable for Monday night's game against the Jets.

McCaffrey has been limited in practice. But when asked if there was any doubt about him playing Monday, he replied, "Nope." As long as McCaffrey is on the field, he is the No. 1 running back and maybe the No. 1 overall player in fantasy. Double-check his status Monday night but all signs point to him playing against the tough Jets defense.