Who are the biggest risers and fallers in numberFire's power rankings this week?

San Francisco 49ers offensive tackle Trent Williams (elbow) is ruled out for Week 17's game against the Seattle Seahawks.

San Francisco 49ers wide receiver Brandon Aiyuk (ankle) won't play in Week 17 against the Seattle Seahawks, per head coach Kyle Shanahan.

San Francisco 49ers tight end George Kittle (foot) is officially active for the team's Week 16 game against the Arizona Cardinals.

San Francisco 49ers quarterback Nick Mullens (elbow) was placed on injured reserve on Friday.

San Francisco 49ers tight end George Kittle (foot) was activated from injured reserve on Thursday.

With only two weeks to go, each of Saturday's contests have massive playoff implications. Who can hold serve?

The San Francisco 49ers signed Josh Rosen to their active roster from the Tampa Bay Buccaneers practice squad on Tuesday.

San Francisco 49ers quarterback Jimmy Garoppolo (ankle) was designated to return from injured reserve but is not expected to be active for Week 16's game against the Arizona Cardinals.

San Francisco 49ers running back Raheem Mostert (ankle) is set to be placed on injured reserve, ending his 2020 season.

San Francisco 49ers quarterback Nick Mullens (elbow) will likely require surgery on his right elbow.

Which widely available defenses could help you to a fantasy championship?