Aaron Rodgers could miss three weeks after initial tests showed a small fracture in the Green Bay Packers star quarterback's collarbone, league sources told ESPN NFL Insider Adam Schefter.

The Packers do not want to make any determination until Rodgers undergoes further testing Tuesday, according to sources.

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

Packers team physician Dr. Pat McKenzie spent several minutes examining Rodgers on the bench before taking him to the locker room for further examination.

Although the swelling in Rodgers' shoulder was too significant to determine the extent of the injury Monday night, a source told ESPN NFL Insider Ed Werder that "it doesn't look good."

"This is the one we couldn't afford to lose," the source told Werder.

Rodgers completed 1 of 2 passes on the opening drive, which resulted in a field goal. Seneca 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.