ARLINGTON, Texas -- The Dallas Cowboys lost two starters in Monday night's 27-20 loss to the Cincinnati Bengals after center Cooper Beebe (concussion) and linebacker DeMarvion Overshown (knee) both left the game with injuries.
Overshown, the Cowboys' second leading tackler, had his right leg rolled into on a Chase Brown run and after getting tended to by the medical staff headed immediately to the locker room with 12:49 to play.
After the game, Cowboys coach Mike McCarthy said Overshown's knee injury is of a "serious nature."
Overshown missed his rookie season last year with a torn anterior cruciate ligament in his left knee. Rookie Marist Liufau replaced Overshown to finish Monday's game.
Beebe is the latest blow to Dallas' offensive line. He initially returned in the second quarter after he was checked out medically, but after further examination in the locker room at halftime, his participation came to an end. Beebe entered Monday having played in 837 of 838 offensive snaps on the season.
With Beebe, a third-round pick, out, Brock Hoffman moved from right guard to center, with T.J. Bass coming in at right guard.
The only Cowboys offensive lineman to not miss time because of injury this season is right tackle Terence Steele.
On Monday, the Cowboys placed Pro Bowl right guard Zack Martin on injured reserve, as he is scheduled Thursday for season-ending surgery on his right ankle.
Left guard Tyler Smith was out one game this campaign with a knee injury, while rookie Tyler Guyton has missed time with numerous injuries. Guyton was active for the Bengals game, but the Cowboys started veteran Chuma Edoga at left tackle.
Beebe won the center job in training camp in a competition with Hoffman.
Hoffman has started the past three games at right guard with Martin out because of his injuries.