Dallas Cowboys offensive linemen Zack Martin, Cameron Erving go down with injuries

ARLINGTON, Texas -- Plagued by injuries on the offensive line all season, the Dallas Cowboys lost right tackle Zack Martin and left tackle Cameron Erving within four plays of each other on the first drive of Thursday's game against the Washington Football Team.

Martin was ruled out with a calf strain, while Erving suffered a knee sprain. Both will be re-evaluated on Friday.

Erving went down with a right knee injury at the 10:27 mark of the first quarter. Martin appeared to suffer a left calf injury with 8:33 left in the quarter. Both players went directly to the locker room, although Erving later returned to the sideline, in uniform but without his helmet. Martin was on the injury report last week because of a calf injury, but he was not on it this week.

Brandon Knight took over for Erving, and the Cowboys have Terence Steele, who started the first nine games at right tackle, replacing Martin.

Martin moved to starting right tackle for the first time in his career last week at the Minnesota Vikings after earning Pro Bowl honors in each of his first six seasons at right guard. He played right tackle in the second half of the Cowboys' Week 3 loss at the Seattle Seahawks. Martin missed the first meeting against Washington because of a concussion.

Erving suffered a knee injury in the season opener and missed five games. He has started the past five contests at left tackle.

Left tackle Tyron Smith played just two games this season before going on injured reserve with a neck injury that required surgery. Right tackle La'el Collins did not play a game this campaign because of hip surgery. Center Tyler Biadasz is on injured reserve because of a hamstring strain but is expected to return in a few weeks.

The Cowboys have not had the same starting offensive line configuration for more than two games this season. They have been forced to use 14 different line combinations.