LAKE FOREST, Ill. (AP) -- Chicago Bears middle linebacker D.J. Williams will miss the remainder of the season because of a chest injury.
Williams ruptured his left pectoral muscle tendon during Thursday's win over the New York Giants.
Coach Marc Trestman was not sure on Friday how the injury occurred. Williams, signed in the offseason to help replace Brian Urlacher, left in the third quarter, the latest injury for a defense that's had its share. The Bears visit Washington next week, and with Williams out, rookie Jonathan Bostic figures to start in his place.
Season-ending knee injuries to defensive tackle Henry Melton and his replacement Nate Collins, not to mention a turf toe injury that's kept Stephen Paea out of the past two games, have forced Chicago to do some major shuffling in the interior. Corey Wootton had to move inside from defensive end and Julius Peppers has been seeing time there, too.
Besides those issues, Pro Bowl cornerback Charles Tillman has dealt with groin and right knee problems in recent weeks. The knee issue kept him out of Thursday's game, although Trestman said he would have been able to play if the game was on Sunday.
Even when the Bears were healthy, they had some issues on defense, particularly with their pass rush. They rank 30th in the league with eight sacks. Julius Peppers hasn't dominated the way he did in the past, and he's not getting much help from the rest of the line.
Now, they're trying to fill major gaps in the lineup, and the list just grew again with Williams' injury.
''We're not making excuses, but again, we're sitting there without Charles,'' Trestman said. ''We're sitting there without Stephen. We've got some young guys in there working. They haven't worked (with) Peppers. They haven't worked with Shea (McClellin) as much. Corey is inside, working inside. But I do believe that just experience-wise, playing 36 minutes (against New Orleans) and the type of game we played on Sunday did have a residual effect on our defense last night.''
As for Williams, he started four of the six games he played and had 35 tackles and two sacks. In 10 seasons with Denver and Chicago, he has 921 tackles, 22 1/2 sacks, 15 forced fumbles, seven fumble recoveries and two interceptions.
He was getting sort of a second chance when he signed a one-year deal with Chicago in March after missing nine games with Denver last season while serving a pair of league-mandated suspensions. The Broncos released him on the eve of free agency, freeing them of his $6 million salary.
He served a six-game punishment for violating the league's policy on performance enhancing drugs and three games for an alcohol-related arrest in 2010 that led to a conviction in August 2012.
In Chicago, he had some major shoes to fill. The Bears were moving on after parting ways with Urlacher, the eight-time Pro Bowl pick and longtime face of the franchise.
Complicating matters for Williams, he did not play in the preseason because of a calf injury. That created opportunities for Bostic, who showed some promise.
Now, he'll have a bigger role.
''He's going to get a lot of work on Monday and during the week,'' Trestman said. ''It's the next-man-up mentality and I think he's mentally ready to take on playing that position. The experience that he had will certainly help him down the road.''
The injury news wasn't all bad for the Bears. Trestman said strong side linebacker James Anderson should be OK after hurting his back against the Giants.
''There's nothing serious there,'' Trestman said.
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