Manningham, who suffered a concussion on Monday night against St. Louis, has undergone a battery of tests and examinations this week, but has yet to be cleared to return to practice by the team's medical staff.
"He couldn't practice so we will see," coach Tom Coughlin said. "We will continue to follow protocol, and as soon as he is clear, he will go."
Coughlin didn't have an update on Manningham's status, and wouldn't address if he'd be able to play on Sunday. The coach added that Manningham has been in meetings with the team.
Asked if Manningham needs to practice before he plays, Coughlin responded, "Everyone needs to practice to play. Depending on how well he reacts to the material, we would make a decision on if he did play, what would be the role."
Manningham suffered the concussion in the first half and said his neck "stiffened" up, but he was held out of the second half after taking a baseline test. He was examined by independent neurologist Dr. Teena Shetty on Tuesday and will continue to follow protocol for players who suffer head injuries before being cleared.
"He feels better even now, but he has to go through a whole bunch of things and every one of them, and rightfully so, has to be signed off on," Coughlin said Wednesday. "And that's not the case just yet. We will see what the next day brings."
In two games for the Giants this season, the 25-year-old Manningham has seven receptions for 105 yards. Last season, the fourth-year pro set career-highs in receptions (60), receiving yards (944) and touchdowns (nine).
Coughlin said that if Manningham is out, Brandon Stokley, Victor Cruz, Jerrel Jernigan and Devin Thomas will all be asked to step up. The rookie Jernigan has yet to dress for the Giants this season but could be a candidate to step in with Domenik Hixon (knee) already out and Mannigham potentially unable to play.
"Everybody has to step up because we will have a role for each of them," offensive coordinator Kevin Gilbride said. "None of them can do all the things Mario does, but each of them can do some of the things he does. We will ask things of those individuals to do what they are capable of doing."
Gilbride said the Giants will try to expand Stokley's role "little by little." The 35-year-old, who recently signed a free-agent contract with New York, has 338 career receptions in 13 seasons as a pro.
"We are hoping to increase and broaden what we ask him to do but we have only had one day of practice because we lost yesterday," Gilbride said. "We will see today and tomorrow and Saturday we will make an assessment and ask of him the things that he can do. Certainly we will expand his role a little."
Cruz, a second-year pro who made his first NFL reception on Monday night, sees Mannigham's possible absence as an opportunity to get on the field, run some routes and hopefully get some looks.
"It's definitely a big opportunity," said Cruz, who plays predominantly in the slot but could shift outside opposite the team's top playmaking receiver, Hakeem Nicks. "You know what we're going up against. We're going up against a pretty good defense and a pretty good secondary, so you wanna be ready."
With Nicks likely to see double teams from the Eagles star-studded secondary, which features Nnamdi Asomugha, Asante Samuel and Dominique Rodgers-Cromartie, others are going to have to rise to the occasion -- even if they haven't done anything in quite a while.
"It should be a shot for me to get on the field, run some routes and hopefully get some looks," said Thomas, who hasn't had an NFL reception since 2009 when he was with the Washington Redskins. "It's been a long-time coming and I should be ready to do my part."
Defensive end Osi Umenyiora (knee), rookie cornerback Prince Amukamara (foot) and reserve defensive tackle Jimmy Kennedy (knee) also did not practice. Center David Baas (lower leg) was limited, while tight end Travis Beckum (hamstring) practiced in full after being limited on Wednesday.
Beckum has yet to appear in a game this season.
Mike Mazzeo is a frequent contributor to ESPNNewYork.com.