Cowboys FB Daryl Johnston will miss the rest of the season because of further neck problems related to 1997 surgery on a herniated disk.
Johnston, 33, conceded the latest problem, discovered in tests Wednesday, could end his career.
"It is going to be a tough decision," he said. "That will be considered at the end of the season. . . . The strange thing is I thought after making it through last season, I'd be okay."
Johnston had surgery six weeks into the 1997 season to fuse two vertebrae in his neck. The procedure left the area above the fused vertebrae vulnerable.
Johnston said he had a burning sensation in his neck during Sunday's season-opening victory over the Redskins. It was the first time he felt such a sensation, known as a "burner," since the surgery.
R. WILLIAMS UPDATE: Rookie RB Ricky Williams practiced with the Saints yesterday but remained questionable for Sunday's game against the 49ers because of a left ankle sprain last week.
Williams, who sat out almost all of the preseason after he sprained the same ankle in the first preseason game, said he is eager to return to the lineup.
"I feel fine running, but I'm not sure, you know, if I can take a hit," said Williams, who was injured early in the Saints' season-opening victory over the Panthers. "Hopefully I'll get out there and play and get a chance to see what I can go through."
Meanwhile, the Saints removed Darren Mickell from the reserve-retired list and will ask the NFL for a two-week roster exemption to evaluate the defensive end. . . .
Jaguars RB Fred Taylor performed only limited work in practice and remained questionable for Sunday's game against the Panthers with a sprained left foot. . . .
Titans QB Steve McNair, with some mild stiffness and spasms in his lower back, watched practice but is expected to play Sunday against the Browns.
SPIELMAN HIRED: Chris Spielman, who retired from the NFL last month because of injuries that left him temporarily paralyzed, has been hired as a studio analyst for Fox Sports Net's NFL pregame show.
Spielman, 33, signed a two-year contract and made a guest appearance Sunday, when "NFL This Morning" made its debut at 11 a.m. on the cable channel's lead-in to the Fox network pregame show.