The San Francisco 49ers have lost starting defensive tackle Alfred Collins for the entire 2026 season after the second-year lineman tore a patellar tendon during practice in Melbourne.

Collins suffered the injury during Tuesday’s session at AAMI Park and had initially been listed as a limited participant because of a knee problem. Further examination revealed the full extent of the damage and brought his second NFL season to an end before it had begun. Head coach Kyle Shanahan confirmed the diagnosis on Wednesday, less than 48 hours before the 49ers face the Los Angeles Rams in the first NFL regular season game staged in Australia.

“We’ve lost two D-linemen pretty much for the year after [roster] cuts and before the first game, which has been a huge challenge,” Shanahan said. “I’m hurting for Alfred. It was real unfortunate for him.”

The injury compounds a difficult opening week for a San Francisco defensive front already without Sam Okuayinonu, who broke his foot shortly before the team travelled to Australia. Okuayinonu requires surgery and has been placed on injured reserve, with the 49ers uncertain whether he will be able to return this season. Mykel Williams, the franchise’s first-round selection in 2025, also begins the campaign on the reserve/physically unable to perform list as he continues to recover from the torn ACL that ended his rookie season.

Those absences leave Osa Odighizuwa as the only established starter available on the interior, with C.J West or rookie Gracen Halton is expected to replace Collins against the Rams, although Halton has himself been limited by an ankle injury. Undrafted rookie James Thompson Jr missed San Francisco’s first official practice of the week with a hamstring problem, further reducing the available options. The 49ers could elevate Sebastian Valdez or Kevin Givens from the practice squad before the game.

The injuries are particularly damaging because they occurred after the league-wide roster reduction, when most immediately available replacements had already joined practice squads elsewhere. San Francisco has therefore travelled to the other side of the world with little opportunity to make a substantial addition before facing Matthew Stafford and a Rams offense carrying championship expectations.

Collins had been selected 43rd overall from Texas in the 2025 draft and appeared in all 16 games during his rookie season. He recorded 17 tackles, one sack, four quarterback hits, an interception and two forced fumbles while gradually assuming a larger role against the run. His development formed part of San Francisco’s attempt to rebuild a unit that finished last in the NFL with only 20 sacks last season. Instead, the 49ers will begin the new campaign relying upon players with limited experience around the returning Nick Bosa.

Bosa is expected to face Los Angeles after recovering from the right ACL tear he suffered last September, but the three-time Defensive Player of the Year has been limited during practice and Shanahan has not yet determined how many snaps he will play following almost a year away from competition. His return was intended to restore the pressure San Francisco had been unable to manufacture without him, but Collins’ injury now places a greater burden upon Bosa before the edge rusher has rebuilt full game conditioning.

Defensive coordinator Raheem Morris must also integrate late arrival Khalid Kareem, who joined the practice squad following Okuayinonu’s injury and could be elevated for the opener. Keion White and rookie Romello Height are among the remaining options on the edge.

Los Angeles, meanwhile, will be without Aaron Donald, whose comeback has been delayed while he continues rebuilding his conditioning after two years in retirement. Myles Garrett, however, has been cleared to make his Rams debut on the defensive front despite injury doubts in the run-up to the game.