It suddenly appears the Giants will be going into their home opener Sunday against the Bills at MetLife Stadium without their top receiver. Sterling Shepard sustained a concussion in the season-opening 35-17 loss to the Cowboys and is in the protocol program.

Shepard was targeted seven times and came away with six receptions for only 42 yards. He was on the field for 68 of the 69 offensive snaps but he did not come out unscathed.

“He’s getting tested,” coach Pat Shurmur said Monday before the results were in. “He has to go through some of the testing. It appears he might be in the protocol here. Each guy is different, as you know. We’ll just have to see how it goes.”

Another starter on offense, right guard Kevin Zeitler, came out of the game with what Shurmur described as “a little shoulder deal we’re getting more information on. We don’t think it will be long term and it may be not much at all. He’s fine though, in my mind he is.”

Zeitler left the locker room Sunday with his left shoulder wrapped.

In addition, outside linebacker Kareem Martin was forced out of the game with a sprained knee.

Players in the concussion protocol are tested every day and it is not likely Shepard will be symptom-free in time to get back for this next game.

Shepard cannot be replaced in a Giants offense already operating without the services of a starting receiver, Golden Tate, who is serving a four-game suspension for violating the NFL policy on performance enhancing substances. That absence forced Cody Latimer into the starting lineup and made Shepard the top target for defenses to stop. If Shepard is unable to play against the Bills, the attack directed by Eli Manning takes a huge hit. Manning mentioned Russell Shepard as next in line. Bennie Fowler is also in the mix. What depth the Giants have at the position gets that much more depleted.

“Hopefully we get him back,” Manning said. “If not, Russell Shepard is a guy that’s been in the offense and played well and done some good things for us. He’ll have to step in, and so hopefully we can get Sterling back for this week.”