GREEN BAY, Wis. -- Quarterback school is back in session with the Green Bay Packers.

Newly signed veteran Seneca Wallace is going to have to brush up on the playbook in a hurry to get ready to back up Aaron Rodgers for Sunday's season opener in San Francisco.

There's a new third quarterback in Titletown, too, after Scott Tolzien was signed to the practice squad Monday.

Both quarterbacks just happened to be with the 49ers before getting picked up by the Packers. How convenient.

"I think any time players are (from) a former organization, there's always (a thinking that) immediately they're going to tell you everything about the 49ers," coach Mike McCarthy said. "Scott and Seneca both are more focused on getting ready for the game so they definitely can give you insight."

More so Tolzien than Wallace. Tolzien was a backup the last two years for the 49ers, but never played in a game. Wallace was only in San Francisco for a week this preseason, competing for a backup job behind Colin Kaepernick.

But it's Wallace who's going to be Rodgers' understudy. It's quite a turnaround from last week, when he was languishing behind Kaepernick, Colt McCoy and B.J. Daniels on the 49ers depth chart.

After being drafted by the Seahawks in 2003 out of Iowa State, Wallace went on to play seven seasons in Seattle. He's also had stops with the Browns and Saints.

In 21 starts and 62 career games, Wallace has completed 59 percent of passes (452 of 764) for 4,808 yards and 31 touchdowns, along with 18 interceptions.

In a relatively young locker room, Wallace, a 10-year veteran, immediately becomes the most experienced player on offense. Only defensive tackle Ryan Pickett has more NFL experience with 13 seasons.

It's that experience that drew McCarthy to his new backup. Wallace had time in a West Coast offense in Seattle under former coach Mike Holmgren, who used to coach the Packers. McCarthy said Wallace ran similar no-huddle schemes in Cleveland. Also, Wallace was drafted in Seattle while current Packers general manager Ted Thompson was the vice president of football operations there.

With Wallace and Tolzien, Green Bay is starting anew in its quest to find a capable backup to Rodgers after already jettisoning three candidates in the last several weeks. Graham Harrell is now with the Jets. Vince Young was cut over the weekend. B.J. Coleman was released after Wallace was signed.

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