Heartbroken by the setback, Bosa shared a broken heart emoji in an Instagram post.
This marks Bosa's second ACL injury since entering the NFL as the second overall draft pick in 2019. He tore his left ACL in 2020 during his second season. This time, it's his right ACL.
The 49ers now face the challenge of generating an effective pass rush without their veteran defensive end anchoring the edge of the defensive front.
"You don't just replace a guy like Nick," head coach Kyle Shanahan said via a conference call on Monday. "Everyone's got to continue to get better at everything. The same thing I'd be preaching if we did have Nick, too. When you lose your better players, it gets harder, but I also expect, throughout this year, all of our players to get better as it goes, and that's stressed that much more when you lose a great one like Nick.
"Lots of guys, obviously, will have to step it up as it goes, but I believe that'll be more by committee than any individual."
The silver lining: the injury was clean, with no additional damage to Bosa's knee. While his recovery will be lengthy, he is expected to make a full recovery and potentially be ready for the start of the 2026 NFL season.
"I was told it was as clean as it gets," Shanahan said. "So, in terms of if you have an ACL, I was told that it was the kind that you want."
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