IRVING -- Fullback Tony Fiammetta is going to miss Sunday's game against Washington because of an illness.
That takes away one of the key parts of the resurgence of the Dallas Cowboys' running game, which has averaged 176.3 yards in the past four games behind the running of DeMarco Murray.
Told Fiammetta had been ruled out, Murray said, "That's not good."
The Cowboys also wonder how long Fiammetta will be out. Coach Jason Garrett said the team hasn't gotten a handle on the nature of the illness.
"We're trying to get to the bottom of what it is," Garrett said. "He's been sick all week long. We're just kind of monitoring those symptoms, and we're just going to continue to do that and see what the origin is."
Garrett said it's too early to say whether Fiammetta might miss the Thanksgiving Day game.
Fiammetta missed two other games with a hamstring injury, against Detroit and New England. The Cowboys rushed for 113 yards against the Lions and 77 against the Patriots.
He was not on the roster in the season opener against the New York Jets, when the Cowboys rushed for 64 yards.
The Cowboys have used tight end John Phillips as a blocking back. They have a rookie fullback on the practice squad, seventh-round pick Shaun Chapas.
Offensive guard Montrae Holland also missed a day of practice this week with illness.
Ryan praises Spencer
Defensive coordinator Rob Ryan said Anthony Spencer is ready to have a big game. Spencer's sack and strip of Washington Redskins quarterback Rex Grossman sealed the Cowboys' victory in the first meeting between the teams this season.
"His angles are better rushing the passer," Ryan said, noting Spencer's work with Leon Lett and Charles Haley this season. "You're going to see a dynamic rusher. I think it's going to show up this week. I really believe all his hard work is going to pay off. He's going to jump off, and everybody like, 'Wow! Where did this production come from?' Well, it's coming, and it's coming fast."
Spencer is sixth on the team in tackles, has four sacks, two tackles for loss, 14 quarterback pressures and two forced fumbles.
Backup quarterback Jon Kitna (back) missed a second day of practice Friday and is listed as doubtful for Sunday's game, so third-string quarterback Stephen McGee will likely be on the active roster.
McGee has been active only three times, twice in the games immediately after Tony Romo suffered a fractured rib and punctured lung against San Francisco, and against Seattle. He has not appeared in any games this season.
"It's life in the NFL as a backup quarterback," McGee said. "Opportunities are random. You never know when they're going to come, how they're going to come, what the situation is, where it's going to be. You've just got to always go about your business the same way. Your approach has got to be the same. I think if you do that, then when it does happen, you're as best ready as you can be."
Running back Felix Jones was limited in practice again Friday and was listed as questionable for Sunday's game. Jones has missed the past four games with an ankle injury. If he plays, he is an option to return kickoffs, Jason Garrett said.
Left guard Kyle Kosier (foot) was also listed as questionable.
Receiver Miles Austin (hamstring) and cornerback Mike Jenkins (hamstring) are out.
Linebacker Sean Lee said he again will play with the cast that covers his left hand, protecting his dislocated wrist.
Cowboys quarterback Tony Romo and Oakland Raiders running back Michael Bush were voted FedEx Air and Ground players of the week.
Carlos Mendez, 817-390-7760