Jordan Raanan of ESPN.com reported the news, though Raanan noted Beckham will go through his pregame workout.
Adam Schefter of ESPN added the following: "Asked chances of OBJ playing tonight vs. Cowboys, one source texted, 'What are the chances of you going to Cuba next month for vacation?'"
Gary Myers of the New York Daily News noted Beckham hasn't practiced since he sprained his left ankle Aug. 21.
The loss of Beckham for the Giants' showdown with their NFC East rivals is a significant one considering he made the Pro Bowl in each of his first three seasons in the league. He surpassed the 1,300-yard mark all three years and is coming off a 2016 campaign in which he tallied a career-high 101 catches for 1,367 yards and 10 touchdowns.
"We have some weapons," quarterback Eli Manning said, per Myers. "We still got guys who can make plays. Odell is a terrific player. You want him out there. But if he can't go, we have a lot of faith in Brandon [Marshall] and Evan [Engram] and [Sterling] Shepard and Roger Lewis, guys who have made plays for us, know what they're doing, and we will be in good shape."
As Manning said, wide receivers Marshall, Shepard and Lewis and tight end Engram will be asked to shoulder more of the load should Beckham be on the inactive list.
Marshall stands out as a six-time Pro Bowler who has largely been a No. 1 option during his career. He will have to fill that role Sunday if Beckham doesn't play.