GREEN BAY, Wis. -- Clay Matthews’ old nemesis -- the dreaded hamstring injury -- has returned, and now Randall Cobb has it, too.

And it has left the Green Bay Packers with questions about whether their defensive standout and one of their key receivers will be available for Sunday’s game at Atlanta.

Neither Matthews nor Cobb did much during the portion of Thursday’s practice that was open to reporters. Both were in pads, but other than the stretching period to start the session, the two were largely spectators. At one end of the Don Hutson Center, Matthews was on one knee during the lengthy jog-through period. At the other, Cobb watched the offense run through its plays. When that period ended, Matthews returned to the elliptical machine he rode during Wednesday's practice, while Cobb watched his fellow receivers do individual drills.

Cobb never mentioned his injury during a session with reporters on Wednesday, but it was conducted before the Packers released their injury report, which offered the first news of Cobb’s new malady. Previously, he had been listed with a back/neck injury in advance of the last two games, but he played in both.

Matthews, who battled hamstring injuries early in his career, already missed the Week 3 game against the Lions because of the injury.

“[Is it as bad as before the] Detroit game? I hope not,” Packers coach Mike McCarthy said before Thursday’s practice. “I think the plan for him is going to be more in a limited fashion today.”

Matthews admitted earlier this season that his return to his natural outside linebacker position could put more strain on his body than when he played inside linebacker from the middle of 2014 through the end of last season. Matthews did not miss any games during his stint at inside linebacker. Matthews played only 27 of the 48 defensive snaps in last Thursday’s victory over the Bears.

The Packers already know they won’t have their top remaining cornerback, Damarious Randall, against the Falcons after he underwent surgery to repair his groin injury last week. Fellow cornerback Quinten Rollins also did not practice for the second straight day. If they don't have Rollins, it will make it that much tougher to slow down the NFL's leading receiver, Julio Jones.