FLOWERY BRANCH — Sam Baker, the Falcons’ starting left tackle, will miss three to four weeks with a back injury.

Baker already missed the Falcons’ previous game, against the Lions on Oct. 23.

“You know how backs can be,” coach Mike Smith said.

Will Svitek has been practicing with the first team at left tackle in place of Baker. Smith said he is “very comfortable” with Svitek at the position. The Falcons signed veteran Kirk Chambers last week when they lost Mike Johnson (foot) for the season. Chambers has played both guard and tackle in the NFL.

Tony Gonzalez (back) did not participate in practice Wednesday. Smith said he expected the tight end to be back on the field Thursday. Center Todd McClure and defensive end John Abraham did not practice as part of a maintenance plan.

Wide receiver Julio Jones (hamstring) was limited in practice. He missed the past two games before the bye week with the injury. Defensive back Christopher Owens (concussion) returned to full practice.

Smith absolved

Antone Smith didn’t do it.

The reserve running back was called for an illegal block that wiped out Eric Weems’ 104-yard kickoff return for a touchdown against the Lions.

“It wasn’t Antone,” special-teams coordinator Keith Armstrong said. “I won’t comment on who it was. I will come to his defense and say it wasn’t Antone.”

The television broadcast showed Smith pushing a Lion to the ground when Weems was already up the field on his way to an apparent score.

Cox getting ready

Fullback Mike Cox, who was signed last week after Ovie Mughelli was placed on injured reserve, has learned much of the system and will see some action against the Colts on Sunday.

“It’s not very complicated,” offensive coordinator Mike Mularkey said. “It’s a pretty user-friendly system. I know that [running backs coach] Gerald Brown has spent a lot of time with him. He’ll get ample work this week.”

In three seasons with the Kansas City Chiefs, Cox played in 39 games and made 17 starts. Cox, who played at Georgia Tech from 2004-07, is mostly a blocker. He had just four carries for three yards and 22 catches for 125 yards. He had just 10 carries in college.

He’ll share the fullback duties with Jason Snelling.

Jones’ return

It appears that Jones will return to the lineup after missing the past two games with a hamstring injury. In Jones’ absence, the Falcons established their running game. Michael Turner ran for 122 and 139 yards, respectively, in wins over the Lions and Panthers.

On Wednesday, quarterback Matt Ryan was asked if it was fair to say that the Falcons’ offense has gotten away from its running roots in order to fit Jones into the game plan.

“It’s easy to say that because the last two weeks that he’s been out we’ve been able to win those games,” Ryan said. “With that being said, when you look at what we did the last couple of weeks, I think the approach was similar in the first five weeks, we just didn’t execute as well or play as well.”

Staff writer D. Orlando Ledbetter contributed to this article.