FLOWERY BRANCH, Ga. — Atlanta Falcons rookie offensive tackle Sam Baker will have surgery on his lower back on Thursday, leaving his status for the rest of the season uncertain.

"We really don't want to put a timeframe in terms of how long before he returns," said Falcons coach Mike Smith, who called the surgery "minor" when he announced plans for the procedure after Wednesday's practice.

"After the procedure, I think we'll have a better idea then," Smith said.

Baker missed last week's game at Philadelphia with what was called a hip injury. When Baker did not respond to treatment, he was scheduled for appointments with two specialists.

The Falcons would not reveal details of the surgery or even say where the procedure will take place. Smith said the surgery will not be performed in Atlanta.

Baker, from USC, was the 21st overall pick in the first round. He was the Falcons' second first-round pick, following quarterback Matt Ryan, the No. 3 overall selection.

Baker has started five games at left tackle. He missed the Sept. 28 game at Carolina with a concussion after leaving two games earlier in the month with head injuries.

Todd Weiner, who started for Baker at Philadelphia last week, was held out of Wednesday's practice with a sore knee.

The Falcons signed veteran free agent Wayne Gandy on Wednesday. The 37-year-old Gandy started for the Falcons in 2006 and 2007, when his season ended with a knee injury in Week 5 at Tennessee.

Smith said Weiner would start at left tackle in Sunday's game at Oakland.

Weiner seemed less confident.

"I think right now it's day to day," Weiner said. "I'll see if I can get a little better each day and get myself ready for Sunday."

Quinn Ojinnaka, who has played in only two games this season, and Gandy split snaps at the position on Wednesday.

"If I can get through a couple of practices and get my wind back, hopefully I can help coach out with whatever he wants," Gandy said.

Though Gandy made 21 starts for the Falcons the last two seasons, his experience under current Atlanta offensive coordinator Mike Mularkey in Pittsburgh was of more interest to Smith.

"Wayne has some familiarity with our verbiage and scheme, having a background in Pittsburgh with Mike," Smith said.

"We'll try to get him up to speed as quickly as we can."

Mularkey was the Steelers' offensive coordinator for Gandy's last two seasons with the team, 2001 and 2002.

"I know about a third of what they are talking about," said Gandy of Mularkey's terminology.

"Football is football. I can catch on in about a week."