SANTA CLARA, Calif. -- On a day when the San Francisco 49ers celebrated the return of one wide receiver, they lost another -- possibly for the season.
Brandon Aiyuk, who has led the Niners in most receiving categories in the past two seasons, suffered what the team fears is a torn anterior cruciate ligament in his right knee in Sunday's 28-18 loss to the Kansas City Chiefs.
If the further testing Aiyuk has coming in the next 24 hours confirms that diagnosis, Aiyuk will need surgery and miss the rest of the season.
"That's what it looks like, but we don't know for sure," coach Kyle Shanahan said. "Been wrong before. So, praying that we are."
At the start of the day, Aiyuk was the only healthy 49er among the team's top three wideouts. Jauan Jennings was ruled out Friday with a hip injury, while Deebo Samuel arrived at Levi's Stadium with an illness that was announced about 30 minutes before the game with the caveat that Samuel was expected to play.
Samuel walked onto the field just before the game started and participated in the coin toss but was moving slowly. He played four snaps but quickly retreated to the sideline and did not return. He had no catches or carries before his day was over.
"Throat, stomach things, just real fatigued," Shanahan said. "Struggled to breathe, couldn't catch his breath ... he kept trying to fight through it, but once he was struggling with the breathing and everything, we had to shut him down."
While the Niners are hopeful that Jennings and Samuel will be back for next week's game against the Dallas Cowboys, Aiyuk's situation appears more serious.
With 48 seconds left in the second quarter, Niners quarterback Brock Purdy found Aiyuk between two Kansas City defenders for a gain of 15 yards. Chiefs defensive backs Chamarri Conner and Trent McDuffie converged on Aiyuk as he took a low hit, leaving his knee in a precarious position.
Aiyuk stayed down as Niners medical personnel came out to help before he was able to get up, slowly limp to the sideline and head to the medical tent. He went to the locker room soon after and a return was ruled out as the third quarter opened.
He had two catches for 23 yards at the time of his departure, leaving the receiver duties to veterans Chris Conley and Ronnie Bell and rookies Ricky Pearsall and Jacob Cowing.
"It sucks," tight end George Kittle said. "I love Brandon Aiyuk, the energy that he brings, what he can do on the football field, routes, catching the ball. He's an incredible football player ... You can't really replace, in my opinion, one of the best receivers in the NFL."
The 49ers signed Aiyuk to a four-year, $120 million extension in August after an extended contract dispute that almost resulted in him being traded to multiple teams, including the Pittsburgh Steelers and Cleveland Browns.
In 2023, Aiyuk had 75 receptions for 1,342 yards and seven touchdowns en route to second-team All-Pro honors. But he was off to a slower start this year with 25 catches for 374 yards and no scores.
Still, Aiyuk's loss is no small thing, especially when paired with the other significant injuries that continue to pile up for the Niners. If Aiyuk misses an extended period, he would join 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) among key 49ers to be out for a significant amount of time.
That would also put additional pressure on Pearsall, the No. 31 pick in April's draft, to produce quicker than expected. Pearsall made his debut Sunday, just 50 days after suffering a gunshot wound to the right side of his chest in an attempted arm robbery in San Francisco.
"What BA does for our offense and who he is and as a teammate and the brother of ours, man, it's sad," Purdy said. "Wish him nothing but the best and praying for him. So that's my guy. And when he goes down like that, obviously we have other guys that can step up and do their job really well ... we all just got to come together as a group collectively, the receiver unit and all of us."