San Francisco 49ers Pro Bowl edge rusher Nick Bosa left Sunday’s game against Arizona with a knee injury, from which he did not return.

Initial tests done by the team’s training staff came back negative, but after an MRI on Monday, it was reportedly determined Bosa torn his ACL and will miss the rest of the 2025 NFL season, according to ESPN’s Adam Schefter.

Bosa was off to a hot start this season, already having two sacks in San Francisco’s first three games. He left Sunday’s win over Arizona late in the first quarter with two tackles and a forced fumble. The All-Pro defensive end left the field and was seen motioning to the stands with a thumbs-down signal as he was led to the locker room.

Serious knee injuries are nothing new for Bosa as he missed the majority of his second year in the NFL after suffering a torn ACL during Week 2 of the 2020 season. The 49ers finished that season 6-10, missing the postseason after making it to the Super Bowl a year earlier. Bosa returned from his ACL injury in 2021, to help the Niners make it back to the NFC championship game where they lost to the Rams.

Advertisement

In 2021, Bosa started all 17 games for San Francisco, made his second Pro Bowl in three years and recorded 15.5 sacks. Since entering the league in 2019, Bosa has he fourth most sacks in the NFL. He led the league in sacks during the 2022 campaign while being named first team All-Pro.

The 49ers are not the deepest team in terms of edge rushers backing up Bosa. Right now, Bryce Huff and Sam Okuayinonu are in line to replace Bosa while he recovers from injury.

This story will be updated.