We Are San Francisco

Nick Bosa Sustained Calf Injury in Practice

The 49ers defensive star could miss several weeks of play after being injured on Thursday.

Updated on Sept. 25, 2026 in Football

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San Francisco 49ers star defensive player Nick Bosa is sidelined with a calf injury, casting uncertainty over his availability for the upcoming game against the Seattle Seahawks. AI Illustration. Upload story photo >

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San Francisco fans face a defensive setback as star Nick Bosa deals with a new calf injury. The injury, sustained during practice, threatens his availability for the upcoming Week 5 matchup against the Seattle Seahawks.

Why it matters

The team is already managing a significantly depleted defensive front with six players currently on injured reserve. This injury compounds the challenge of fielding a competitive defense while the team prepares for the upcoming schedule.

There are now six members of the defensive front seven on injured reserve, including five defensive linemen. It remains unknown if Bosa will join them on the list through Week 7.

The players

Nick Bosa

The star defensive end for the San Francisco 49ers.

The details

Nick Bosa sustained the calf injury during a practice session this past Thursday. The team is now evaluating his status, with projections suggesting he could miss multiple weeks of game action. If placed on injured reserve, Bosa would be sidelined at least through Week 7, potentially missing the game against the Seahawks in Week 5.

Timeline

  1. Thursday: Nick Bosa suffered a calf injury during practice.

  2. Sunday: San Francisco plays the Arizona Cardinals.

  3. Week 5: San Francisco plays the Seattle Seahawks.

  4. Week 7: Bosa remains out if placed on injured reserve.

  5. Week 8: San Francisco has a bye week.

Across the Bay

This injury follows the pattern established by the ongoing 2026 defensive front seven injury crisis. It extends the personnel strain currently impacting the unit's depth.

Fans should monitor the team's status report closely before Sunday's game against the Arizona Cardinals. You can expect defensive lineup changes if Bosa is sidelined for the Week 5 matchup against the Seattle Seahawks.

The takeaway

The team must now navigate a critical stretch of games with a significantly thinned defensive front. Watch for official roster announcements regarding the injured reserve list ahead of the Week 5 kickoff.

Further reading

For more updates on team personnel and upcoming matchups, visit our Football section.

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Do you believe a professional sports team can recover from multiple injuries to key players?