Manningham stated emphatically that he expects to play on Monday night against the New Orleans Saints, but Bradshaw and Boley are less certain.
Boley, who missed last week's loss to Philadelphia with a hamstring injury, ran for the first time on Friday but did not sound optimistic about playing against the Saints.
"I don't want to put myself in a situation where I hurt the team or I hurt myself. I'd rather miss another week than miss a few more weeks," he said on Friday.
Bradshaw "started out moving around well" on Friday, according to Giants coach Tom Coughlin, but it is unclear if he tested his injured foot any further. Bradshaw has missed the past three games with a fractured foot but said he was targeting Monday's game for his return.
He was not available to speak with reporters on Friday.
Coughlin said it is possible that both Boley and Bradshaw will suit up on Monday.
One player who won't see the field is left tackle Will Beatty. Beatty underwent surgery to repair a detached retina in his right eye on Thursday. A timetable for his return isn't yet available.
"Nothing's been declared yet. I've been playing some [left guard] during practice, playing next to Boothe, next to Stacy Andrews] as well," Diehl said. "This is nothing new for me. This is part of being a guy who can play multiple positions. If things happen, if guys go down, I'm capable of moving. Obviously, I know what to do at left tackle."
Diehl spent a majority of the past four seasons at left tackle but was forced to move to guard due to injuries last season.
If Bradshaw is out, look for Brandon Jacobs to get the bulk of the carries. Jacobs was booed loudly after running for just 21 yards on 12 carries in the Giants' loss to Philly last week.
He said afterward that he didn't care about the boos but said of fans: "That's the best thing they do around here is boo," which rubbed some observers and fans the wrong way.
On Friday, Jacobs, unprompted, was highly complimentary of Giants fans.
"We've got a lot of people that's pulling for us. We've got a lot of great fans that's out there and want us to go out there and do good," Jacobs said. "For all of the people that have supported us from Day 1, we've got to go out there and do our best for them."
If Boley can't suit up, rookie Mark Herzlich may get his second straight start at middle linebacker.
Herzlich finished with four tackles (two solo) on Sunday against Philadelphia.
"I thought he was commanding in the huddle. I thought he was decisive in his reads and I thought he gained a lot of respect from his teammates by the way he played that football game," defensive coordinator Perry Fewell said of Herzlich.
Ian Begley is a regular contributor to ESPNNewYork.com.