The San Francisco 49ers lost another key player off their banged-up defense with linebacker Tatum Bethune sidelined for the rest of the season with a groin injury.

The 49ers (12-5) have a chance to get two star offensive players back for a wild-card game at Philadelphia (11-6) on Sunday with coach Kyle Shanahan saying Pro Bowl left tackle Trent Williams (hamstring) and receiver Ricky Pearsall (knee, ankle) will be evaluated later in the week after missing last week's game.

Bethune had stepped in at middle linebacker after star Fred Warner went down with an ankle injury in Week 6 and was the team's defensive play-caller on the field for the eight games he started this season.

Bethune got hurt during a Week 18 loss to Seattle and Eric Kendricks will step in to fill that role when the Niners face the Eagles.

Kendricks was signed to the practice squad in late November and played 46 snaps on defense the past three games after being promoted each week to the game day roster. The 33-year-old Kendricks has started 143 regular-season games and six playoff games since entering the league with Minnesota in 2015.

"I'm real confident in Eric," Shanahan said. "He's been here long enough. These games he has gotten in the last couple weeks he's done a good job, and I'm glad that we've got him for this situation."

Shanahan said that Warner is making progress but that any potential return for him wouldn't come until the NFC title game at the earliest if the 49ers can win their next two games.

The San Francisco offense struggled last week against Seattle's without Williams and Pearsall as the running game never got going and there were few open receivers downfield.

The Niners have averaged just 2.8 yards per carry running to the left side since Williams got hurt on the opening snap in Week 17.

Pearsall leads San Francisco with eight catches on throws at least 20 yards downfield. Quarterback Brock Purdy didn't attempt a single deep pass last week in his absence.

In other injury news, linebacker Dee Winters (ankle), LB Luke Gifford (quadriceps) and defensive lineman Keion White (hamstring) will all be evaluated throughout the week to determine whether they can practice or play. Safety Ji'Ayir Brown (ribs) and defensive tackle Kalia Davis (knee) are day to day.

The 49ers will also open the practice window this week for second-year receiver Jacob Cowing, who has been out since injuring his hamstring in August.