The San Francisco 49ers have confirmed Brandon Aiyuk has torn the anterior cruciate and medial collateral ligaments in his right knee and will miss the rest of the season.
Star wide receiver Aiyuk was injured near the end of the second quarter as the 49ers lost a Super Bowl LVIII rematch against the Kansas City Chiefs, 28-18, on Sunday.
That result dropped them to 3-4 after an injury-plagued start to 2024, with running back Christian McAffrey another big-name absentee.
Head coach Kyle Shanahan suggested after the game that Aiyuk's injury looked serious, and the team's worst fears were confirmed when he undertook additional tests on Monday.
"I talked with him last night, just calling him at his house," Shanahan said of Aiyuk. "He was hurting, just bummed out, exactly how you'd expect.
"But he's a strong dude and spiritual guy and believes everything happens for a reason, so he'll be all right.
"He was definitely a little down last night, and I was just telling him how bad I felt for him and just let him know we're all here for him through this."
Fellow wideout Deebo Samuel, meanwhile, was limited to four snaps against the Chiefs after feeling unwell and was subsequently checked into hospital with a form of pneumonia.
"I think it started acting up in the middle of the night Saturday night or early Sunday morning and then it just evolved as the day went on," Shanahan said of Samuel.
"Once we found out he had the fluid in his lungs after the game, then I believe they sent him over there."
There is no timeline for Samuel's return to action, with the Niners' next outing pitting them against their long-time rivals, the Dallas Cowboys, on Sunday.