Zack Martin in concussion protocol, will not return

Charean Williams
ProFootball Talk on NBC Sports

Cowboys right guard Zack Martin will not return. He entered concussion protocol after a hit late in the first half.

Joe Looney replaced Martin on the final series of the first half.

Martin, center Travis Frederick and left tackle Tyron Smith made the All-Pro team last season. Only Frederick has made it through the season without an injury.

Smith returned Thursday after missing the previous two games with a groin injury. He also has dealt with a back injury.

Smith was called for a holding penalty, negating a 34-yard touchdown run by Dak Prescott in the third quarter.

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