The San Francisco 49ers will have to move forward without one of their top players on offense after Brandon Aiyuk went down against the Kansas City Chiefs. After further testing on Monday, Aiyuk's injury is officially season-ending, according to NFL insider Jordan Schultz.

Aiyuk went down with an injury after taking an awkward hit near the end of the first half of the 49ers' loss on Sunday. He was carted to the locker room before being ruled out for the rest of the game. After the contest was over, head coach Kyle Shanahan said that the team feared a torn ACL for their star wide receiver. He will now begin rehabbing to get ready for next season.

Aiyuk signed a 4-year, $120 million contract extension just before the season started after a lengthy contract dispute. Trade rumors swirled around the star wide receiver for most of training camp before he eventually agrees to the deal to remain in San Francisco long-term.

Losing Aiyuk is a major blow to the 49ers' passing game. He is their best separator on the outside and is elite at creating separation against tight coverage even when nothing is originally open on the play. Without him in the lineup against the Chiefs, it was much more difficult for Brock Purdy to find open receivers against a great defense.

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Aiyuk was coming off of two consecutive 1,000-yard seasons, including a stellar 2023-24 campaign that saw him explode for 1,342 yards and seven touchdowns.

Aiyuk's injury is the latest in a string of them for the 49ers' skill position players. San Francisco was forced to play on Sunday without Jauan Jennings and Deebo Samuel, and running back Jordan Mason was playing through a shoulder injury. The team is still waiting for star running back Christian McCaffrey to return as well.

McCaffrey's return becomes especially important with Aiyuk out, as he might be the second best true route runner on the team. Until they get him back, the passing game will be extremely difficult to navigate with both Aiyuk and McCaffrey sidelined.