Thomas was lifted on a stretcher and carted off the field during halftime after he was injured covering a Redskins kickoff return on the final play of the first half. There was no immediate word on his injury, but his neck was stabilized as he was removed. Thomas was moving his legs as he was attended to by trainers.
The Giants later said Thomas was up and walking around after suffering a neck injury but would be evaluated and held out the rest of the game, according to the New York Daily News. Coughlin described the tests for Thomas as "precautionary."
Ballard was hurt on the first play of New York's final drive of the opening half, a 15-yard gain, and limped to the sideline. The team announced at halftime he would not return.
Ballard has 38 catches and four touchdowns this season, his second as a pro and first as a starter.
The Associated Press contributed to this report.