SANTA CLARA, Calif. – Less than 24 hours after wide receiver Brandon Aiyuk injured his right knee against the Kansas City Chiefs, the San Francisco 49ers got the bad news they expected.

Aiyuk tore the anterior cruciate ligament and medial collateral ligaments in his right knee, requiring surgery and ending his 2024 season after just seven games, coach Kyle Shanahan announced Monday.

Additionally, the illness that limited receiver Deebo Samuel to four starts against the Chiefs is technically a form of pneumonia, Shanahan said. Samuel has some fluid buildup in his lungs and remains at a local hospital after his check-in Sunday evening.

“I think it started happening in the middle of the night on Saturday night or early Sunday morning and then it evolved as the day went on,” Shanahan said. “After the game, when we found out he had fluid in his lungs and stuff, I think they sent him there.”

Shanahan said there is no timeline yet for when Samuel could return, although that should provide clarity in the coming days.

Aiyuk is not expected back at all this season. Further testing on Monday confirmed what Shanahan expected on Sunday evening. After a 28-18 loss to the Chiefs, Shanahan said all signs pointed to a torn ACL, but that a closer look still needed to be taken and that the Niners were “praying” they were wrong. They weren’t.

Aiyuk’s injury happened with 48 seconds left in the second quarter. Quarterback Brock Purdy squeezed a pass to Aiyuk between Kansas City defensive backs Chamarri Conner and Trent McDuffie for a gain of 15 yards. When Conner and McDuffie got to Aiyuk, his knee appeared to hyperextend.

Niner medical staff immediately ran onto the field to care for Aiyuk, who lay there for a few minutes before slowly limping to the sideline and the blue medical tent. He was soon taken to the locker room on a cart.

Aiyuk had two catches for 23 yards at the time of the injury, which occurred during a relatively slow start to the season. With his season over, Aiyuk won’t be able to reach 1,000 receiving yards for the third year in a row. He had 75 receptions for 1,342 yards and seven touchdowns en route to a second-team All-Pro nod last year.

“I talked to him last night, I just called him at his house,” Shanahan said. “He was in pain, just disappointed, just as you’d expect. But he’s a strong guy and a spiritual guy and believes everything happens for a reason, so he’ll be fine. But last night I was definitely a little down and I just told him how bad I felt for him and just let him know that we’re all here for him.”

The Niners signed Aiyuk to a four-year, $120 million extension in August after a lengthy contract dispute. He finishes this season with 25 catches for 374 yards and no scores.

Aiyuk’s ACL is the latest in a growing list of injuries for key 49ers. Running back Christian McCaffrey (Achilles tendonitis), linebacker Dre Greenlaw (torn Achilles tendon), defensive tackle Javon Hargrave (torn triceps) and safety Talanoa Hufanga (torn ligaments in his wrist) are among the other key Niners to miss a significant amount of time.

“It sucks,” center Jake Brendel said Sunday. “Any injury like this to any of your weapons, whether on offense or defense, just sucks. I feel like as a roster we just have to respond. Whoever is next on the roster has to step up and go for it to ensure that there is no attack.” adversity and productivity on offense.”

With Aiyuk lost for the season, the 49ers hope to get Samuel and Jauan Jennings back for Sunday night’s game with the Dallas Cowboys. Jennings did not play against Kansas City due to a hip injury suffered in an Oct. 10 win against the Seattle Seahawks.

If they can’t get Samuel and Jennings, or both, for the Dallas game, the Niners would again have to turn to a group that includes rookies Ricky Pearsall and Jacob Cowing, second-year wideout Ronnie Bell and veteran Chris Conley, who also plays daily with an ankle injury.

“He was in pain, just disappointed, just as you’d expect. But he’s a strong guy and a spiritual guy and believes everything happens for a reason, so he’ll be fine. But last night I was definitely a little down and I just told him how bad I felt for him and just let him know that we are all here for him because of this.”

49ers coach Kyle Shanahan on his conversation with WR Brandon Aiyuk

“With Jauan and Deebo, I’m not sure if we get them back this week or not,” Shanahan said. “So it was a good start for those guys and there should be many more to come.”

Tight end George Kittle, who picked up most of the pass-catching slack against the Chiefs with six catches for 92 yards, is also day-to-day with a foot sprain.

Elsewhere on the injury front, Shanahan said the Niners don’t expect to get McCaffrey, Greenlaw or kicker Jake Moody back this week either.

“Christian is still making progress with his rehabilitation,” Shanahan said. “He hasn’t had any setbacks, so it’s all good news so far. I’d be surprised if I get him back this week, but hopefully the bye week goes well and I’ll have a much better chance there right after the bye week.” .”

Shanahan indicated that Moody could also return after the Week 9 bye, but Greenlaw will likely last a little longer.