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Lions center Travis Swanson missed practice Wednesday with a concussion.

(AP File Photo)

ALLEN PARK -- Detroit Lions center Travis Swanson is dealing with a brain injury and his status for Sunday's game against Chicago is in doubt.

It's unclear when he suffered the concussion, considering he played all 70 offensive snaps in the win against the New Orleans Saints over the weekend.

If Swanson can't go on Sunday, the Lions have a natural replacement in rookie Graham Glasgow. He actually played center at Michigan, and was drafted in the third round to compete with Swanson at the position.

But Swanson has improved significantly this year -- he's been among the 10 best centers in the league almost wire to wire per ProFootballFocus -- and wound up beating out Glasgow for the job. He's been perhaps Detroit's most consistent offensive lineman of the season.

Instead, Glasgow's initial playing time has come by replacing the underperforming Laken Tomlinson at left guard. Tomlinson likely would be promoted back into the lineup at that position if Glasgow moves inside.

Elsewhere on the injury report, running back Theo Riddick missed practice because of a wrist injury, while star defensive end Ezekiel Ansah missed practice because of more ankle trouble. That's a disconcerting development. Ansah already missed three games with a high ankle sprain, then limited several weeks after his return by the injury.

He still does not have a sack.

Tight end Eric Ebron (knee), receiver Marvin Jones (quad), linebacker DeAndre Levy (knee), running back Dwayne Washington (ankle), linebacker Tahir Whitehead (knee) and special teams ace Don Carey (hamstring) all practiced but were limited.