GREEN BAY, Wis. -- It looks like it will be at least eight weeks before JC Tretter sees the field for the Green Bay Packers.

The team is expected to use its one-and-only spot on the injured reserve/designated to return list on the player who was supposed to be its opening-day starting center.

"The timeline is such that it would make sense to designate him for return," Tretter's agent, Alan Herman, said Tuesday.

Tuesday was the first day teams could use that designation on a player, and it would not show up on the NFL's official transactions until Wednesday. Herman said late Tuesday afternoon he had not been told the move had been made yet.

Tretter sustained a fracture to his left knee during the Packers' Aug. 22 preseason game against the Oakland Raiders.

Herman originally said Tretter's injury, which does not require surgery, should heal in six weeks. That coincides roughly with when Tretter could return to practice under the temporary IR rules, which allow a player to practice after six weeks and play after eight.

If the move is made this week as expected, the first game Tretter could return for is Nov. 9 against the Chicago Bears. It comes a week after the Packers' bye.

The Packers used the injured reserve/designated to return on Randall Cobb last season after the receiver broke his tibia in Week 6 against the Baltimore Ravens. Cobb could have returned in Week 15 but did not come back until the regular-season finale against the Bears.

The move allows the Packers to use Tretter's roster spot on another player, but unlike the regular injured reserve list, Tretter can return later in the season. The most likely candidate for that roster spot is practice-squad center Garth Gerhart.

Rookie fifth-round pick Corey Linsley, who did not take a single snap with quarterback Aaron Rodgers in the preseason, will start in Tretter's place. At this point, the Packers have only seven healthy offensive linemen on their roster.