Manning, who has started the last 82 games, was held out of practice Wednesday so he can get treatment on his plantar fascia, a band of connective tissue that runs along the bottom of the foot and inserts into the heel.
"If I feel like I can go out and play at a high level and help the team and do everything I can do, and they don't have to limit the game plan or say you can't do this or that, I'll go out there and play," Manning said. "I'm not going to do anything that will put myself in harm for making this worse down the road."
Manning admitted his heel bothered him occasionally the last few weeks. However, he never had pain like he felt in the fourth quarter Sunday when he set up to throw against Kansas City and literally had to hop because it so was intense.
"It never bothered me at practice," said Manning, who has led the Giants to a 4-0 start. "It never kept me from doing anything."
Veteran David Carr, the No. 1 overall pick in the 2002 draft, would replace Manning if he could not play. He has 79 career starts, but none since 2006 with Carolina.
"The game plan is not going to be adjusted," coach Tom Coughlin said. "He has been a starter in this league. He has been very much into what we have done from the standpoint of a plan each week. We wouldn't taper a whole lot."
Manning had the most basic treatment Wednesday: electric stimulation and ice. He also was fitted for an orthotic for his shoe. He watched videotapes of the Raiders' defense, went over this week's game plan, planned to watch tape of practice, discuss it with his receivers and then go over his notes.
His biggest concern though was his heel, which he said is improving. Manning said he felt less pain than on Monday and Tuesday and that he was moving around better. He said he was in no pain while talking in front of his locker.
He has asked the team's medical staff whether playing this weekend might make his injury worse. They told him they just don't know.
"As an athlete you know when something is bothering you and when something is going to get worse or not, and I'll make that decision," Manning said.
Wait and see is the way Manning described his plans for both practice the rest of this week and the game.
"I feel like I have been practicing well and playing good football and been in a rhythm the last couple of weeks," Manning said. "You don't want to go out there when you are injured and you can't do everything you want to do and move the way you want, and all the sudden you get bad habits and bad mechanics and you're throwing the ball differently."
Manning said he would like to practice some time this week, but noted he could play without practicing.
When Manning hurt the A-C joint in his right shoulder early in the 2007 season, he missed practice on Wednesday and Thursday and took only half the snaps on Friday before starting against Green Bay.
"I was probably more worried about my shoulder than this," Manning said. "It was my throwing shoulder and I couldn't even throw when I hurt that. I couldn't throw the ball 10 yards. I know I can throw the ball now, it's the moving around and all the other things I have to take care of."
Coughlin said Manning doesn't need to practice to play.
"He will know everything," Coughlin said. "While he is in here today, he will have a [video] machine in front of him. His tape time will probably be as good as or maybe more than a normal week. Yeah, he will study hard."
TE Kevin Boss did not practice because of a sprained right ankle. He said it is improving. ... Chase Blackburn will start at weakside linebacker with Michael Boley expected to be sidelined a month following surgery on his right knee. ... HB Danny Ware practiced for the first time since dislocating his left elbow on the opening kickoff in the first game of the season.