GREEN BAY, Wis. (AP) Green Bay's defense had all it could handle the first time it faced Cam Newton.
Three years after Newton had a breakout performance against Green Bay in his second NFL start, the Packers will have to try to contain the Carolina Panthers' versatile quarterback without at least one key defensive player.
Starting cornerback Sam Shields won't play Sunday, when the Panthers come to Green Bay for a game between division leaders.
Shields, who leads Green Bay with two interceptions, sustained what coach Mike McCarthy on Friday called a knee strain in the a comeback win over the Miami Dolphins on Sunday.
McCarthy didn't know if the injury would keep Shields sidelined more than a game.
''He's getting better, though,'' McCarthy said.
Tied for the NFC North lead, the Packers (4-2) might also be without their other starting cornerback against the NFC South-leading Panthers (3-2-1).
Tramon Williams sustained an ankle injury in the last game. Like Shields, Williams didn't practice this week, but McCarthy said the team isn't counting out the veteran player from playing Sunday. Williams is questionable on the injury report.
''We're still going through the process, but he's better today than he was yesterday,'' McCarthy said. The Packers didn't practice Friday, but estimated Williams would have been a limited participant had they been on the field.
''I think tomorrow will be the biggest indicator, obviously with us going (back) to the practice field,'' McCarthy said. ''As I stated earlier in the week, we'll give Tramon Williams every opportunity all the way up to game time to play.''
Williams has missed only one game in his eight-year pro career.
That came in Week 2 of the 2011 season, when a shoulder injury kept Williams from playing the last time Green Bay and Carolina met. Green Bay won that game at Carolina, 30-23.
McCarthy referred to Williams as ''an old-school pro'' for his high rate of durability, playing in 128 of Green Bay's 129 games (including playoffs) since 2007.
''I don't think there's any question when we got back here Monday that he was going to do everything that he could to play in this game,'' McCarthy said.
Green Bay spent this week preparing the young tandem of Davon House and Casey Hayward to fill in at cornerback if it has to play without both Shields and Williams on Sunday.
House and Hayward have played a lot in situational roles on defense this season.
House has made two starts as the nickel cornerback, contributing an interception and a forced fumble. Hayward had his first interception of the season in the last game and also has a fumble recovery.
That type of production when they have been called on gives defensive coordinator Dom Capers comfort if House and Hayward are needed for enhanced roles Sunday.
''I feel very fortunate,'' Capers said. ''I think the depth in our secondary is probably as good as it has been.''
NOTES: Packers DE Datone Jones is out for a second straight game with an ankle injury. ''He's struggling laterally right now, and until he gets that back, it doesn't make sense to push it forward,'' McCarthy said. ... LB Jamari Lattimore is questionable Sunday after suffering a neck injury in the last game. Brad Jones, who lost his starting job to Lattimore after the first week of the season, is next on the depth chart.