The 49ers won big against the Buccaneers on Sunday but came away from the game with a significant loss.
All-Pro safety Talanoa Hufanga sustained a season-ending torn ACL. Head coach Kyle Shanahan confirmed the injury with reporters on Monday. There is no other structural damage to Hufanga's knee.
Hufanga injured his knee while planting his right leg in pass coverage.
The injury is a significant blow to a strong San Francisco defense.
Hufanga, 23, earned a full-time starting job with the 49ers last year in his second NFL season. He started all 17 games, tallying four interceptions, two forced fumbles, nine passes defended, two sacks and 66 tackles. He earned Pro Bowl and first-team All-Pro honors for his efforts. A versatile defender who makes plays all over the field, he will not be easily replaced in San Francisco's secondary.
Rookie backup Ji'Ayir Brown took Hufanga's place in the lineup and made an immediate impact. He intercepted Bucs quarterback Baker Mayfield then broke up a fourth-down pass in the end zone to help seal the win in the fourth quarter.
His effort earned praise from head coach Kyle Shanahan.
"I thought he did a hell of a job," Shanahan said. "To lose a player like Huf in a game and for him to come in and step it up big and make two huge plays."
Brown is in line to step into a starting role with critical games against the Seattle Seahawks and Philadelphia Eagles coming up on the 49ers schedule.