It's a revolving door at linebacker for the Packers as they begin preparations for Sunday's big divisional showdown with the Minnesota Vikings at Lambeau Field.  Brady Poppinga is out after undergoing arthroscopic knee surgery this week and AJ Hawk didn't practice Wednesday with a groin injury.  However, Clay Matthews returned on a limited basis off a hamstring pull and Brandon Chillar, who missed three games with a shoulder injury, also returned to the practice field.    Defensive end Mike Neal has also been ruled out of the Minnesota game with a shoulder injury, but Ryan Pickett appears over his ankle sprain which forced him out of the Miami contest.  Nick Collins (knee) and Donald Driver (quad) missed practice but should be available on Sunday.   Mark Tauscher also returned on a limited basis  after mising the past two games with his shoulder injury.  At least the Packers got some new players on the field.  Three players are coming off the physically unable to perform list and worked out for the first time with the team this season.   Click on the audio report below for more: