Aaron Rodgers has broken collarbone

Aaron Rodgers confirmed Tuesday that he has a broken left collarbone, an injury that could sideline the Green Bay Packers quarterback into December.

Rodgers said on his weekly radio show that a timetable for his return has not been set, and Packers coach Mike McCarthy said Tuesday that the team is operating with "a week-to-week" mindset.

"We're still going through the process of testing," Rodgers said Tuesday on ESPN 540 in Milwaukee. "But we do know that the collarbone is fractured and we still have not talked about or discussed any long-term prognosis."

And while McCarthy said he is preparing Seneca Wallace to start Sunday, he would not officially rule out Rodgers.

The sliver of good news for the Packers: McCarthy indicated the injury won't end Rodgers' season.

"I'm relieved, no doubt," McCarthy told reporters at Lambeau Field. "With the new information that was given today, everybody felt better about it. How long? We don't have our hands around a timeline yet, but I know Aaron is very optimistic and he'll do everything he can to get back in a timely fashion."

Earlier Tuesday, league sources told ESPN NFL Insider Adam Schefter that the 2011 league MVP could miss three weeks.

A source told ESPN.com that Rodgers will not need surgery but that his status remains uncertain for Green Bay's game on Thanksgiving against the Detroit Lions.

The Packers can wait until Friday to officially rule out injured players, but McCarthy said, "I'm preparing Seneca to be the starter; that's the way our game planning has gone."

Yet he seemed to leave open a glimmer of miraculous hope.

"But let's not kid ourselves, if [Rodgers] walked in your office and asked for the ball on Saturday, what would you do," he asked rhetorically. "So, we'll just see what happens."

Rodgers suffered the injury in Monday night's 27-20 loss to the Chicago Bears. He landed on his left shoulder when he was sacked by defensive end Shea McClellin on the game's opening series.

"I'm in some pain," Rodgers told ESPN 540. "It's obviously disappointing what happened last night with the injury and the loss. ... Holding out hope this will be a quick heal, but this is a significant injury."

Rodgers was 1-of-2 passing on the opening drive, which resulted in a field goal. Wallace, signed by the Packers during the first week of the regular season, replaced Rodgers on the second series, a drive that ended in an interception.

With 6:54 left in the third quarter, Rodgers returned to the Packers' sideline in street clothes and received a loud ovation from the crowd.

"When I walked back on that field -- I'm getting a little choked up here just thinking about it -- that was one of the top five moments of my career," Rodgers said Tuesday. "The reception I got from the fans was pretty special."

Green Bay (5-3), which fell into a three-way tie with Chicago and Detroit atop the NFC North, has been ravaged by injuries this season.

The Packers already were without Pro Bowl linebacker Clay Matthews (thumb), wide receiver Randall Cobb (fibula) and tight end Jermichael Finley (neck) for Monday night's game.

Wallace, who finished 11-of-19 for 114 yards, an interception and no touchdowns, is the only other quarterback on the Packers' active roster.

Rodgers has missed just two games since becoming the Packers' starter in 2008. He played with a separated left (non-throwing) shoulder during the 2008 season and did not miss a game.

In 2010, Rodgers missed a Week 15 game at New England after suffering a concussion in the previous week's game.

The three-time Pro Bowler also sat out the 2011 regular-season finale, when the Packers opted to rest Rodgers against the Lions -- a game in which backup Matt Flynn passed for 480 yards and six touchdowns.

Wallace, 33, owns a 6-15 career record as a starter and has not won a game as a starter since Oct. 3, 2010, as a member of the Cleveland Browns.

ESPN.com Packers reporter Rob Demovsky, ESPN Stats & Information and The Associated Press contributed to this report.