49ers Lose Star Pass Rusher Nick Bosa for Season Due to Knee Injury

The San Francisco 49ers will have to overcome the loss of their star defensive end as they look to maintain their strong start to the season.

Apr. 20, 2026 at 2:28am

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A cubist, geometric painting depicting a fractured, multi-perspective view of a 49ers defensive play, with sharp planes and angles representing the loss of their star pass rusher Nick Bosa to a season-ending knee injury.The 49ers' defense faces a major challenge in trying to replace the disruptive presence of star pass rusher Nick Bosa after his season-ending knee injury.Santa Clara Today

The San Francisco 49ers have suffered a major blow with the news that star defensive end Nick Bosa will miss the rest of the season after tearing the ACL in his right knee during Sunday's game. Bosa, who was the 2022 NFL Defensive Player of the Year, has dealt with knee injuries in the past, including a torn ACL in his left knee that cost him the 2020 season. The 49ers will now have to rely on a committee approach to try and replace Bosa's immense production and impact on their defense.

Why it matters

Bosa is one of the best defensive players in the NFL and a key part of the 49ers' success. His absence will be a major challenge for the team as they look to maintain their strong start to the season and make a push for the playoffs. The 49ers have already dealt with several key injuries this year, and now they must find a way to overcome the loss of their star pass rusher.

The details

Bosa suffered the season-ending knee injury during the 49ers' Week 3 game on Sunday. This is the second time in his career that Bosa has torn an ACL, having previously suffered the same injury in his left knee in 2020. The 49ers will now have to rely on a committee approach to try and replace Bosa's production, with first-round rookie Mykel Williams, veterans Bryce Huff and Yetur Gross-Matos, and several others expected to step up.

  • Bosa suffered the torn ACL in his right knee during the 49ers' Week 3 game on Sunday, September 24, 2026.
  • Bosa also missed the 2020 season after tearing the ACL in his left knee in Week 2 of that season.

The players

Nick Bosa

The star defensive end for the San Francisco 49ers, who was the 2022 NFL Defensive Player of the Year after leading the league with 18.5 sacks. Bosa has now suffered season-ending ACL tears in his left and right knees during his NFL career.

Fred Warner

The 49ers' veteran linebacker who expressed his disappointment over Bosa's injury and the challenge of trying to replace the team's star pass rusher.

Kyle Shanahan

The head coach of the San Francisco 49ers, who acknowledged the importance of Bosa to the team's defense and said they will have to find ways to fill the void left by his absence.

Mykel Williams

The 49ers' first-round rookie defensive lineman who is expected to be part of the committee approach to replace Bosa's production.

Bryce Huff

A veteran defensive end who will also be counted on to help make up for Bosa's absence on the 49ers' defensive line.

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What they’re saying

“I'm sick. I'm so sick for him because he knows what that's like to go through that process of recovery from that injury, which I know he's fully capable of but that doesn't make it any easier. Obviously it's a huge blow to our team, but we move forward. I hate to say next man up mentality because you can't just replace him with one player.”

— Fred Warner, Linebacker

“I'm not going to sit here and say something and make it better. Everyone knows the deal and so we've got to focus on what we've got to get done.”

— Kyle Shanahan, Head Coach

What’s next

The 49ers will need to activate receiver Demarcus Robinson this week after his missed the first three weeks with a suspension, and they can create an open roster spot by placing Bosa on injured reserve.

The takeaway

The loss of Nick Bosa is a major blow for the 49ers, who will have to find a way to overcome the absence of their star pass rusher and defensive leader. While the team has dealt with other key injuries early in the season, Bosa's season-ending ACL tear is an especially difficult challenge that will require a collective effort from the entire defense to try and maintain their strong start.