D.J. Ware, the Giants' No. 3 running back behind Jacobs and starter Ahmad Bradshaw, now will be Bradshaw's primary backup, with seventh-round draft pick Da'Rel Scott going into the third spot. Scott has only played on special teams for Giants (3-1), but he could see his first offensive action in third-down blocking situations.
The Giants are tasked with getting an inconsistent ground game on track against the Seahawks, the NFL's 14th-ranked run defense. Center David Baas has been ruled out with a neck injury, which leaves reserve Kevin Boothe with the responsibility of producing the physicality the interior of the line has lacked so far.
Giants running backs have averaged just 3.3 yards per carry, good for 29th in the league. Ware's cutting style and his 6-foot, 225-pound frame can make people miss, but he doesn't present the punishing entity that Jacobs does.
Meanwhile, the frustration surrounding Jacobs' slow healing is tangible. He injured the knee last week against the Arizona Cardinals and was pulled from the lineup after his fourth-quarter touchdown. He missed all three days of practice this week.
Jacobs said Thursday: "It doesn't feel too bad. I am just waiting for the time when they unleash me and let me do a little running and stuff like that, but I feel good."
"I thought he'd make more progress, but that hasn't been the case," Coughlin said. "I don't know if it's a setback, but there is swelling."
Coughlin confirmed to reporters Friday that Tuck had a setback Thursday, and the lineman's groin injury is more of an issue right now than his neck, according to The Star-Ledger.
The Associated Press contributed to this report.