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 were expecting.

Aiyuk suffered a torn anterior cruciate ligament in his right knee that will require surgery and end his 2024 season after just seven games, a source confirmed to ESPN.

On Monday, further tests confirmed what Niners coach Kyle Shanahan was expecting on Sunday night. After a 28-16 loss to the Kansas City Chiefs, Shanahan said all signs pointed toward an ACL but a closer look was still needed 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. As Conner and McDuffie converged on Aiyuk, his knee appeared to hyperextend.

Niners medical personnel immediately ran on the field to tend to Aiyuk, who stayed down for a couple of minutes before slowly limping to the sideline and the blue medical tent. He was soon taken to the locker room on a cart and a return to the game was ruled out to open the third quarter.

Aiyuk had two catches for 23 yards at the time of the injury in midst of a relatively slow start to the season. With his season over, Aiyuk will not be able to reach 1,000 receiving yards for the third straight year. He had 75 receptions for 1,342 yards and seven touchdowns on his way to a second team All-Pro nod last year.

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

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

"It sucks," center Jake Brendel said Sunday. "Any injury like that to one of your weapons on offense or defense, it just sucks. I feel like as a roster, we just have to respond. Whoever's next on the roster needs to step up and make sure that there isn't a setback and productivity on offense."

The news of the extent of Aiyuk's injury was first reported by Fox Sports.

ESPN's Jeremy Fowler contributed to this report.