SANTA CLARA, Calif. -- The San Francisco 49ers' fears about the injury to defensive end Mykel Williams were confirmed Monday when the club learned that the rookie tore the anterior cruciate ligament in his right knee.
After the Niners' 34-24 victory against the New York Giants on Sunday, coach Kyle Shanahan left little doubt about Williams' likely diagnosis while also trying to offer a hint of optimism that further testing would reveal better-than-expected news in a brief chat with the No. 11 pick in the 2025 draft.
"He's just down, and you never know," Shanahan said after the game. "Hopefully, it's not the worst, but if it is, hey that sucks for this year. But that's all it sucks for. You'll be back next year, and this won't affect you at all."
As it turned out, Williams will need surgery to repair the knee and then must begin a lengthy recovery process before he can return in 2026. On Monday, Shanahan officially confirmed the diagnosis and said lateral meniscus damage was discovered, as well.
Williams suffered the injury with about four minutes left in the game as he pressured Giants quarterback Jaxson Dart. Williams got close to Dart, who threw incomplete to his right. But Williams' knee buckled and he went down. His immediate reaction suggested something was seriously wrong as he grabbed for his right knee and pounded his helmet and the turf in frustration.
Williams was able to slowly walk off the field, but Shanahan said after the game that the team was "worried" about the injury being an ACL tear though an MRI on Monday was needed to confirm it. Williams has started San Francisco's first nine games, averaging 45.4 snaps per contest and posting 20 tackles and a sack while lining up on the edge on early downs and moving inside to rush the quarterback on obvious passing downs.
Williams' ACL tear is the latest blow to a 49ers team that has been ravaged by injuries this season, with many of those ailments hitting the defense in the past month.
With Williams out, the Niners will play their remaining eight games without either of their top two defensive ends from the start of the season, as Nick Bosa tore his right ACL in a Week 3 win against Arizona.
San Francisco also placed defensive end Yetur Gross-Matos on IR Friday because of a hamstring injury and played the past two weeks without edge rusher Bryce Huff. The Niners are also without star linebacker Fred Warner (right ankle dislocation).
As it stands, the only healthy defensive ends on the 53-man roster are Sam Okuayinonu, Robert Beal Jr. and Keion White, whom the team acquired in a trade with the New England Patriots last week. The 49ers elevated end Clelin Ferrell from the practice squad to play against the Giants after signing him last week. Huff is expected to return for Sunday's game against the Los Angeles Rams.
The Niners, who have been seeking more trade help on the defensive line even after adding White and Ferrell, will continue looking into those options leading into Tuesday's deadline.
Though help could be on the way, Niners left tackle Trent Williams made it clear after the win in New York that the injuries are taking their toll.
"Injuries are a part of the game, and everybody deals with it, but we have been bitten particularly hard by the injury bug," Williams said. "We've been able to continue and fight past it. But who knows? You never know when that straw is just enough to break the camel's back."