Tyron Smith left after practice to have an magnetic resonance imaging test on his left ankle.
Smith’s ankle, which he apparently rolled in Sunday’s game at Seattle, bothered him during individual drills Wednesday. The starting left tackle sat out the team portion of practice before heading for tests to determine the severity.
The Cowboys already are without right tackle Doug Free for 3-to-4 weeks after Free fractured his foot during Sunday’s game. Jermey Parnell, expected to replace Free at right tackle, was limited with a chest injury he played through last week.
They signed offensive tackle Tony Hills earlier Wednesday as a swing tackle. Donald Hawkins is the only other tackle on the roster, though right guard Zack Martin played tackle in college.
Smith and Free were among seven key players to sit out practice Wednesday.
Quarterback Tony Romo (back/ankle), running back DeMarco Murray (illness), linebacker Bruce Carter (thigh), linebacker Rolando McClain (groin/personal) and defensive end Anthony Spencer (knee/foot) also missed practice.
Spencer said he hopes to return to practice Thursday.
“I got stepped on during the game, so it’s just a little sore,” said Spencer, who played 29 snaps against the Seahawks.
Carter said he likely will miss his third consecutive game, though he put his quadriceps to the test Wednesday in rehab work.
“Probably not,” Carter said of playing this week, “but I know I’ll be back next week. I felt great running today, cuts and everything.”
Defensive end Jack Crawford (calf) also sat out.
Receiver Dez Bryant (shoulder) and linebacker Cameron Lawrence (thigh) were full participants.