San Francisco 49ers star defensive end Nick Bosa’s season is over due to a torn ACL, head coach Kyle Shanahan confirmed Monday.

Bosa underwent testing after hurting his right knee during Sunday’s victory over the Arizona Cardinals. Imaging showed a clean tear of the ligament, per ESPN.

“You don’t just replace a guy like Nick,” Shanahan told reporters. “Everyone has to get better.”

The five-time Pro Bowl selection was injured in the first quarter while being double-teamed during an Arizona pass play. His knee bent awkwardly as he fell to the ground and he did not return to the contest, giving a thumbs down on his way to the sideline medical tent.

Bosa, 27, had two tackles and a forced fumble before departing. He has two sacks and 17 tackles in three games this season for the 49ers (3-0).

Bosa is in his seventh season with San Francisco. He was the Defensive Player of the Year in 2022 when he recorded a career-high 18.5 sacks. In 85 games (83 starts), he has 64.5 sacks, 91 tackles for loss, 168 quarterback hits, 278 tackles, 13 forced fumbles and two interceptions.

Veteran defensive Bryce Huff, acquired in a June trade with the Philadelphia Eagles, will take over starting duties as the 49ers prepare for Sunday’s date with the visiting Jacksonville Jaguars (2-1).

The news wasn’t all bad for San Francisco on Monday, though. Shanahan also told reporters that quarterback Brock Purdy could return to action this week after missing the last two games due to turf toe.

Purdy, who was a limited participant in practice all of last week, will practice once again this week after he was listed as questionable but did not play vs. Arizona.

“We’ll see if there are any limitations,” Shanahan said.

Mac Jones, who replaced Purdy and has led the 49ers to wins over the Saints and Cardinals in his absence, is day-to-day (knee) after playing through a training camp injury he re-aggravated in Sunday’s game.

–Field Level Media