Gregory was among the seven inactive players after he was listed as doubtful entering the game. He took part in just one limited practice during the week because of a concussion suffered in last week's season opener. Gregory was knocked out of the Week 1 loss to the Carolina Panthers in the second quarter after recording one quarterback pressure.
He did not practice Wednesday or Thursday as he was in the concussion protocol. Gregory was on the field through early pregame warmups Sunday but did not do anything.
Without Gregory, the Cowboys have just eight defensive linemen active against the Giants, with Datone Jones already ruled out with a knee injury.