Bears LB D.J. Williams out for season with ruptured pectoral tendon

The Bears have lost another key member of their defense.

Starting middle linebacker D.J. Williams will miss the remainder of the season with a ruptured left pectoral tendon. A source said Williams will require surgery.

Williams suffered the injury Thursday night against the Giants. He was ruled out in the second half and replaced by rookie Jon Bostic.

Coach Marc Trestman said Bostic will work more with the first-team defense starting on Monday, when players return from a weekend off. Bostic made his defensive debut against the Giants, getting 21 snaps.

“It’s the next-man-up mentality, and I think he’s mentally ready to take on playing that position,” Trestman said. “The experience that he had will certainly help him down the road.”

Starting strong-side linebacker James Anderson, who also plays in the nickel package, also suffered a back injury against the Giants.

“I think he’ll be OK,” Trestman said. “There’s nothing serious there.”

The loss of Williams is another blow to the Bears’ defense.

They’ve already lost defensive tackles Henry Melton and Nate Collins with torn anterior cruciate ligaments in their left knees. Cornerback Charles Tillman (knee) and defensive tackle Stephen Paea (toe) also were inactive against the Giants.