49ers’ Nick Bosa exits win vs. Cardinals with knee injury, gives thumbs-down to crowd

SANTA CLARA, Calif. (AP) — San Francisco star defensive end Nick Bosa left the win over the Arizona Cardinals with a knee injury in the first half and the 49ers are waiting for word on the extent of the injury.

Bosa left the field favoring his right leg after a third-down pass rush in the first quarter. He went immediately to the medical tent and appeared to give a thumbs-down signal to someone in the crowd.

Bosa tested the knee briefly on the sideline before going back to the locker room. He was ruled out of the game at halftime.

Coach Kyle Shanahan said initial tests did not show a tear of Bosa’s ACL, but he will need more tests to completely rule that out and to learn the severity of the injury.

“There is concern because of how he feels,” Shanahan said. “They did the tests and stuff on the sideline. Usually they say whether he definitely did or not. They didn’t say that. But we are concerned with that and keeping our fingers crossed for the MRI.”

San Francisco rookie defensive end Mykel Williams also went back to the locker room in the first half with a wrist injury, but quickly returned. Williams and fellow rookies Alfred Collins and C.J. West helped San Francisco pull out a 16-15 victory.

“Anytime you lose a guy like Nick and he doesn’t come back, that’s a real buzzkill,” left tackle Trent Williams said. “We’re hoping and praying that we get some good news. It’s cliche to say it’s a next man up league, but when you lose a guy like that, you need three or four guys to come in.”

Bosa won the AP NFL Defensive Player of the Year award in 2022 and is one of the most important players on the 49ers. He had two sacks in the first two games this season and has 64 1/2 in his career.

Bosa has made the Pro Bowl in five of his six seasons in the NFL, missing only in 2020 when he went down with a season-ending knee injury in Week 2.

“Obviously he’s one of our best players, so it would be a huge loss,” linebacker Fred Warner said. “I’m hoping for the best news.”

The Niners have been missing several of their biggest stars with tight end George Kittle on injured reserve after hurting his hamstring in the season opener, No. 1 receiver Brandon Aiyuk on the physically unable to perform list recovering from knee surgery and quarterback Brock Purdy missing two games with a toe injury.

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49ers' Nick Bosa exits win vs. Cardinals with knee injury, gives thumbs-down to crowd | iNFOnews.ca
San Francisco 49ers defensive end Nick Bosa takes the field prior to an NFL football game against the Arizona Cardinals, Sunday, Sept. 21, 2025, in Santa Clara. (AP Photo/Sergio Estrada)

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