Green Bay linebacker Clay Matthews (52) is slow to get up after being injured while sacking Pittsburgh quarterback Ben Roethlisberger in the second quarter
Green Bay linebacker Clay Matthews (52) is slow to get up after being injured while sacking Pittsburgh quarterback Ben Roethlisberger in the second quarter at Lambeau Field in Green Bay, Wis., Sunday, December 22, 2013. The Steelers defeated the Packers, 38-31. (Mark Hoffman/Milwaukee Journal Sentinel/MCT)

GREEN BAY -- The Green Bay Packers lost, but they will fight another day.

The only question is whether they'll have enough players to field a competitive team.

Once again, injuries struck key players in the Packers' 38-31 loss to the Pittsburgh Steelers on Sunday at Lambeau Field. And there's a chance they could be without a couple of them when they play the Chicago Bears for the NFC North title Sunday at Soldier Field.

The most serious was to linebacker Clay Matthews, who reinjured the thumb he fractured against Detroit on Oct. 6. For the third time this season, Matthews suffered an injury that knocked him out of the game while sacking the quarterback.

Matthews, who suffered a Bennett's fracture of the thumb and needed to have pins inserted to hold the thumb together, was appearing in his seventh straight game after a four-game absence. He was still wearing a modified cast on his hand to protect the thumb, but it was obvious when he hurt it that he was in tremendous pain.

"It's a similar injury," coach Mike McCarthy said.

Assuming his thumb broke away from the hand at the joint like it did last time, Matthews is likely out for the season. It's a fragile injury and if it isn't treated with surgery and immobilized Matthews could suffer permanent damage.

Matthews had 1 1/2 sacks in his last two games, but he has not been the same player since returning. The Packers used a combination of Nick Perry and Andy Mulumba to fill Matthews' spot.

Perry is dealing with a bad foot and was limited in his snaps.

In addition to Matthews, running back Eddie Lacy reinjured his sprained right ankle. The two times he sprained it -- against Atlanta and Dallas -- he was able to return to the game, but this time he was not.

Lacy had bulled his way on 15 carries for 84 yards and two touchdowns, raising his season total to 1,112 rushing yards, which broke John Brockington's 32-year-old franchise rookie record of 1,105 yards.

James Starks did an admirable job filling in for Lacy, totaling 47 yards on 10 carries and catching a 23-yard screen pass. But the Packers' offense is built around Lacy, and if he can't play against the Bears and their porous run defense, it would be a huge blow to the Packers' chances.

Linebacker Brad Jones continued to struggle with an ankle injury and was in and out of the lineup. Linebacker Mike Neal suffered a stinger but returned.

Cornerback Micah Hyde, who had the best game of his career, contributing both on defense and with 167 kickoff return yards on five attempts, suffered a shoulder injury.

Penalty time: The Packers killed themselves with penalties all game.

They finished with nine for 90 yards. It was the second-most penalties they've had in a game this season and several of them were key factors in the Steelers winning.

"Penalties and turnovers were huge," tight end Andrew Quarless said.

Said Hyde: "They were big. A couple of them were on third down, and you've got to get off the field on third down. It's tough, but in the end we had a chance to win. We all could have made some more plays."

Fortunate call: After Mason Crosby's third-quarter field-goal attempt was blocked, the Packers thought they had squandered a perfect scoring opportunity.

But after the block, the ball was bouncing around and Steelers lineman Ziggy Hood batted the ball out of bounds, which is a penalty. Steelers coach Mike Tomlin thought one of his players had possession of it before Hood batted it out, but the ruling on the field was that no one had possession.

"We ruled that the ball continued to be a loose ball throughout the play," referee Carl Cheffers said. "Batting is an intentional act. It's when you strike the ball, you cannot do that in the direction of your own goal line. So, if you bat the ball forward, it is an illegal act.

"We went back to where the ball was snapped."

The Steelers had a hard time stomaching that call.

"That was maybe the craziest thing I have ever seen in 12 years of football," end Brett Keisel said.

That gave the Packers a first down at the 2-yard line and on the next play Lacy blasted in for the touchdown to give the Packers a 21-17 lead.

Daytime drama: When he spoke after the game, the Chicago Bears had not lost to the Philadelphia Eagles, so McCarthy did not know that the Packers would still have a shot at the playoffs.

He knew that his team had blown a perfect chance. It controlled it's own destiny and couldn't do anything about it.

"I don't know about drama," McCarthy said. "You've got to control your own destiny. We let that opportunity out of our hands and we have to sit and hope Philadelphia beats the Bears.

"It's the reality of where we are in our season. We're kind of a peak and valley football team. That's the way our season has gone. We've had a lot of challenges come our way and good Lord willing, maybe the ball will bounce our way."

Mission accomplished: The Steelers had plenty of motivation after watching two AFC wild-card candidates lose earlier in the day.

"Our mentality hasn't changed," Tomlin said. "We can only control what it is that we can control, to win the games that are presented to us. We haven't done enough of that to this point in the season. We just stayed together and fought."