San Francisco 49ers rookie defensive end Mykel Williams is off to a promising start. Still, they need a bit more from the Georgia product after receiving bad Nick Bosa news on Monday.

Bosa suffered a knee injury in Sunday's 16-15 home win over the Arizona Cardinals. 49ers head coach Kyle Shanahan believed the DE avoided an ACL tear, but a test revealed otherwise. He will now need season-ending surgery, via ESPN's Adam Schefter.

Tests today showed that 49ers Pro Bowl DE Nick Bosa suffered a season-ending torn ACL during Sunday’s win over Arizona, sources tell ESPN. It’s a clean tear, but Bosa now will need season-ending surgery. pic.twitter.com/f6xdHY0iVS — Adam Schefter (@AdamSchefter) September 22, 2025

How Bosa's injury affects 49ers' defense

Bosa, 27, is the 49ers' best defen

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