Cowboys quarterback Tony Romo injured his left (non-throwing) shoulder with 12:07 to play in the second quarter after completing a pass to wide receiver Miles Austin on Monday night.
His return is unknown.
Romo was hit by Giants weakside linebacker Michael Boley, who came on a blitz.
Romo's left shoulder crashed to the turf as Boley tackled him to the ground.
Jon Kitna took over for Romo and his first pass was knocked down. Romo tried to return to the game with about 11:18 to play but associate trainer Britt Brown pulled him back and slowly walked him to the bench area.
Romo took his helmet off and slammed it down lightly. Surrounded by several trainers and team doctors, Romo was then taken into the locker room for further examination.
If Romo misses any extended period of time, it's the first time he hasn't played since the 2008 season when he suffered a broken pinkie, causing him to miss three games.
The return of Kitna was his first snaps since Oct. 5, 2008 when he played with Detroit.