What Happened To Nick Bosa? 49ers Star's Latest Injury Raises Week 3 Concerns

Nick Bosa is back on the injury report, and the timing could not be more unsettling for San Francisco. The 49ers' star defensive end appeared on the practice participation report Thursday with both a knee and a calf issue ahead of Sunday's Week 3 matchup against the Arizona Cardinals. He sat out practice entirely, and for a team already decimated along the defensive line, that absence carries serious weight. Bosa only just returned this season after tearing his ACL in Week 3 of 2025 against this same opponent.  

Is Nick Bosa playing in Week 3 against the Cardinals?

Bosa did not practice on Wednesday, though the team listed it as a scheduled rest day. Thursday's absence was different. He sat out entirely, listed with both a knee and calf concern. Bosa has been managing his knee since training camp opened, and a new calf injury has added a second layer of worry heading into game week. 

The backdrop here matters. In 2025, Bosa sustained a season-ending torn right ACL injury in Week 3 against the Arizona Cardinals. He has now made it back from that surgery in time for the 2026 opener. That comeback alone was a significant achievement. But facing the same opponent in the same week of the season, now listed as a non-participant in practice with a knee issue, the optics are hard to ignore. 

The 49ers have already absorbed serious losses along their defensive front. Starting defensive tackle Alfred Collins is out for the year with a torn patellar tendon. Defensive linemen Sam Okuayinonu and CJ West are both on injured reserve. James Thompson Jr. is dealing with an ankle injury and faces an extended absence. Edge rusher Romello Height underwent surgery on a fractured hand this week and may not face Arizona either. 

Mykel Williams, San Francisco's first-round pick from the 2025 NFL Draft who is also returning from an ACL tear, is on track to come back off injured reserve, but not before Week 4. That means for now, Bosa's presence is essentially carrying whatever is left of this defensive line. 

How important is Nick Bosa to the 49ers' defence?

Bosa's 64 and a half sacks in the regular season rank fourth-most in the NFL since he entered the league in 2019, and his elite pressure rate consistently ranks among the very best in the entire league over that same span. Those numbers explain why a single missed practice sends ripples across the entire 49ers defence. 

San Francisco ranked last in the NFL last season with just 20 sacks across 17 regular-season games. Bosa had two of those before going down in Week 3. Without him, the pass rush simply did not function. The 49ers have had a full offseason to address depth, but the current injury report suggests those problems have not gone away. 

Wide receiver Mike Evans also sat out his second straight practice with a hip injury. He leads the team with nine receptions for 103 yards and one touchdown through two weeks. With receiver depth already thin, San Francisco is staring at potential problems at both ends of the ball against Arizona. 

"You don't just replace a guy like Nick," coach Kyle Shanahan said last year when Bosa was lost for the season. That statement feels just as relevant this week as the team waits to learn whether its best defensive player can take the field Sunday.