O'Hara has a mild sprain of the Lisfranc ligament in his right foot, according to a league source. The center did not practice on Monday and is considered week-to-week.
Head coach Tom Coughlin said O'Hara suffered the new injury during the Giants' 41-35 victory over the Cowboys last Monday night.
Coughlin said "we'll see" when asked if he is optimistic about his center being able to practice this week but it sounds like O'Hara likely will miss this Sunday's game at Seattle.
Coughlin was asked earlier in the day if O'Hara's injury was related to the Lisfranc area of the foot, mid-foot bones which when injured can keep a player out indefinitely. Defensive end Justin Tuck and former Giant Michael Strahan have both been limited by Lisfranc injuries in the past.
"No, I am not using that word," Coughlin had said.
Coughlin said the team doctors told him the injury is mild. If O'Hara is unable to play, the Giants will likely start Adam Koets, who started in place of O'Hara against Tennessee, Chicago and Houston earlier this season.
The Giants have also used guard Rich Seubert at center in practices as well. The Giants were looking forward to having their offensive line intact with O'Hara, who seemed to be getting better from a left ankle injury that had been bothering him since the offseason and kept him out of three games this season. O'Hara has played in four of the Giants' seven games this season. He did play in the last two games against Detroit and Dallas but now will likely miss more time with this latest setback.
Coughlin also revealed that cornerback Bruce Johnson underwent knee surgery last week. Later, the team announced that he was placed on injured reserve, and the Giants claimed defensive end Alex Hall off waivers from the Cardinals. Hall was with the Giants in training camp.
Johnson had seen most of his action on special teams this season.
Tackle William Beatty did do some light work today as he continues to make progress from foot surgery after the season opener. Offensive lineman Kevin Boothe, who the Giants may soon bring off the physically unable to perform list, continues to work his way back and Coughlin is eager to see Boothe practice this week.
Fullback Madison Hedgecock did some work in practice as he makes his way back from a hamstring injury that has cost him the last three games. Tight end Bear Pascoe has started at fullback and played well.
Ohm Youngmisuk covers the Giants for ESPNNewYork.com.