What happened: Kyle Shanahan confirmed the diagnosis Wednesday. The injury occurred during Tuesday's session in Melbourne. [UPI](https://www.upi.com/Sports_News/NFL/2026/09/09/australia-Alfred-Collins-San-Francisco-49ers-out-season/1781788956651/)

Why it matters: The loss leaves a hole at defensive tackle before the season opener.

What to watch: Watch for the replacement plan and how defensive tackle snaps are redistributed.