Rookie backup cornerback Sam Shields (calf) also has been ruled out.
Safety Nick Collins, who sat out practice earlier this week with a nagging knee injury, was upgraded to probable and likely will play.
Barnett is out for the season after suffering a wrist injury similar to the one that ended Brian Urlacher's season last year, two NFL sources told ESPN NFL Insider Adam Schefter. He was injured last week against Detroit.
On offense, the Packers may not have right tackle Mark Tauscher, who is doubtful with a shoulder injury. Packers coach Mike McCarthy didn't rule out Tauscher, saying if Tauscher came up to him on Sunday morning and said he could play he would let that happen. Running back Quinn Johnson (glute) has been scratched.
John Clayton is a senior NFL writer for ESPN.com.