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, twisted his right leg on a run by Chase Brown and, after being treated by medical staff, immediately went to the locker room with 12:49 minutes left in the game.

After the game, Cowboys coach Mike McCarthy said Overshown’s knee injury was “serious in nature.”

Overshown missed his rookie season last year because of a torn ACL in his left knee. Rookie Marist Liufau replaced Overshown and finished Monday’s game.

Beebe is the latest blow to Dallas’ offensive line. He initially returned in the second quarter after a medical examination, but after another examination in the locker room at halftime his participation ended. Beebe entered Monday having played 837 of 838 offensive snaps this season.

After Beebe, a third-round pick, went out, Brock Hoffman moved from right guard to center while TJ Bass came in at right guard.

The Cowboys’ only offensive lineman not to miss any time due to injury this season is right tackle Terence Steele.

On Monday, the Cowboys placed Pro Bowl right guard Zack Martin on injured reserve as he undergoes season-ending surgery on his right ankle on Thursday.

Left guard Tyler Smith missed one game this season with a knee injury, while freshman Tyler Guyton was sidelined 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 started the last three games at right-back while Martin was sidelined due to injuries.