According to ESPN's Jeremy Fowler, tests have confirmed what the San Francisco 49ers feared. Rookie defensive lineman Mykel Williams suffered a season-ending ACL injury late in Sunday's 34-24 win over the New York Giants.
Testing revealed a torn ACL for 49ers rookie DL Mykel Williams as head coach Kyle Shanahan feared, per source.
— Jeremy Fowler (@JFowlerESPN) November 3, 2025
Update: Head coach Kyle Shanahan confirmed the injury during a conference call, adding that Williams also tore his lateral meniscus.
Williams went down in the fourth quarter and was visibly frustrated, pounding his helmet as medical staff attended to him. After being evaluated in the medical tent, he slowly made his way to the locker room.
Mykel Williams walked off the field under his own power after appearing to injure his knee
(via @NFLonCBS) pic.twitter.com/AGJQSuKJcM
— 49ers on NBCS (@NBCS49ers) November 2, 2025
This development marks the latest setback for a 49ers roster already dealing with multiple key injuries, including season-ending losses to linebacker Fred Warner and defensive end Nick Bosa, the team's two top defenders.
For 49ers fans, it's another unfortunate incident at MetLife Stadium, a venue often criticized for its playing surface. Bosa suffered his previous ACL injury there during his second NFL season in 2020.
After Sunday's game, before the severity of the injury was confirmed, head coach Kyle Shanahan said, "You never know, so I said, 'Hopefully, it's not the worst, but if it is, hey, that sucks for this year, but that's all that sucks for you. You'll be back next year, and this won't affect you at all.'"
The 49ers selected Williams with the 11th overall pick in the 2025 NFL Draft. In his rookie season, he recorded 20 tackles (four for loss), three quarterback hits, a sack, and a fumble recovery across nine games.