Blackburn limped off the field during the Cowboys' second touchdown drive of the second half. The Giants staved off a Dallas comeback to win 29-24.
Blackburn had two tackles in the first half. He's backed up by Mark Herzlich.
Reserve tight end Bear Pascoe also suffered an injury, as he sprained his ankle in the first half.
Late in the second quarter, Pascoe was taken to the locker room for X-rays that proved negative, but the Giants say his return is doubtful.
Randy Jennings is a contributor to ESPNNewYork.com.