O'Hara, the leader of the team's offensive line, missed last Sunday's 29-10 loss to the Tennessee Titans with a left ankle and Achilles' tendon injury.
Asked if O'Hara might require surgery, Coughlin added: "I don't think so. We're hoping it's not a surgical issue."
Adam Koets made his first start last weekend, and Coughlin said the lineman did "a fine job." But continuity on an offensive line is particularly important, and with the unbeaten Chicago Bears heading to the Meadowlands on Sunday night, this is a critical week to block well.
"We know what kind of team is coming in here," guard Chris Snee said. "We know how they get after you."
Bulluck, in his 11th NFL season, started two of the previous three games. If he can't go, second-year pro Clint Sintum is the backup at strongside linebacker.
Manningham sustained a concussion against the Titans. Coughlin said he was surprised that Manningham had problems before practice, adding the receiver would go through further tests.
"The nature of it was late Sunday night that he contacted people in the training room," Coughlin said. "He really appeared to be fine Monday when we saw him. We didn't expect that there would be any slowdown in his performance today (in the team meeting). ... There was, so hopefully we can do the tests again and see how that comes out."
Manningham is second on the team with 14 receptions, averaging 17 yards per catch with one touchdown. He's part of a three-pronged receiving unit with Steve Smith and Hakeem Nicks, and Manningham he can't go against the Bears, undrafted rookie free agent Victor Cruz would move up. Cruz was a preseason sensation who mostly has played on special teams during the season.
"I'd like to get in there and try to be myself and hopefully get in there and catch some balls and make some plays," Cruz said. "It means a lot to have an opportunity to go out and play and have an important role in the game and make sure I'm ready not only for myself, but for my teammates."
Copyright 2010 by The Associated Press