Green Bay, WI (SportsNetwork.com) - Green Bay Packers All-Pro linebacker Clay Matthews aggravated a previous injury to his right thumb during Sunday's game against the Pittsburgh Steelers, leaving him likely unavailable for this weekend's winner-take-all Week 17 showdown with the Chicago Bears.

Matthews hurt his surgically repaired thumb while sacking Ben Roethlisberger during the second quarter of the Packers' 38-31 loss to the Steelers. Although head coach Mike McCarthy didn't give a definitive answer on the standout pass rusher's status during Monday's press conference, he didn't sound optimistic that Matthews would play.

"I couldn't give you a timeline, but I think based off the history of what happened the first time, I'm told it's similar to the repeat injury," McCarthy told reporters.

Matthews missed a month of this season after fracturing the same thumb in early October, with the break requiring surgery to repair.

The four-time Pro Bowl selection leads the Packers with 7 1/2 sacks despite missing four games with the prior injury.

McCarthy also declined to update the availability of starting quarterback Aaron Rodgers, out since fracturing his left collarbone when Green Bay faced the Bears at Lambeau Field on Nov. 4, but did state a decision as to whether or not the 2011 NFL MVP will return for Sunday's critical matchup will be made prior to Friday.

"I think it's important for us to make a quicker decision," he said. "This has obviously been frustrating, stressful for Aaron, rightfully so. But also, [for] our football team, I want them to know who the quarterback is going to be."

The winner of Sunday's clash in Soldier Field will reach the playoffs as the champion of the NFC North, with the loser eliminated from the postseason.