The Lions started essentially four rookies Sunday against Chicago: running back Kevin Smith, fullback Jerome Felton and right tackle Gosder Cherilus, plus right guard Manny Ramirez, a second-year player whose only experience was one game on special teams last season.

Defensive end Cliff Avril and linebacker Jordon Dizon saw significant playing time on defense, though Dizon's came when the game was out of hand.

PLAYER NOTES

-- QB Jon Kitna didn't practice for the second straight day Thursday because of a back problem. He rode a stationary bike at the beginning of practice while the others drilled in pads, then walked onto the field gingerly. Offensive coordinator Jim Colletto said Kitna could be a game-time decision Sunday at Minnesota.

-- QB Dan Orlovsky has been listed as limited in practice Wednesday and Thursday because of knee and ankle injuries, but he seems fine and should be able to start if Jon Kitna can't play.

-- CB Travis Fisher did not practice for the second straight day Thursday because of a knee injury and seems questionable for Sunday.

-- RG Stephen Peterman will not play Sunday because he is too limited by the cast on his broken left hand, offensive coordinator Jim Colletto said. Manny Ramirez will start in his place for the second straight game.

-- DT Shaun Cody returned to practice Thursday after sitting out Wednesday as a precaution because of a concussion.

-- LG Edwin Mulitalo also returned to practice Thursday after sitting out Wednesday as a precaution because of a concussion.

-- WR Calvin Johnson was listed as limited Thursday because of a knee injury, but he is expected to play Sunday.

-- WR Roy Williams practiced fully Thursday after being limited Wednesday by a hip injury.

GAME PLAN: The Lions have to find some way to keep from falling behind so badly. Four games, four awful deficits - 21-0, 21-0, 21-3, 31-0. They tried a no-huddle offense Sunday against Chicago, but expect them to go back to a more traditional running game with play-action passes, roll outs and bootlegs. The defense must stop running back Adrian Peterson, but even if the Lions find a way to do that, they could be in trouble. They rank last against the pass. They have only four sacks and no interceptions this season.

MATCHUPS TO WATCH: Lions LT Jeff Backus vs. Vikings RDE Jared Allen -- Backus allowed another sack Sunday against Chicago. Allen, who led the NFL with 15.5 sacks last season, has two sacks this year. All of Detroit's quarterbacks are coming off injuries - Jon Kitna (back), Dan Orlovsky (ankle) and Drew Stanton (thumb). If Backus can't contain Allen, it could lead to a fate even worse than sacks. If Orlovsky plays, he would be an inviting target for Allen. He is the least mobile of the Lions' QBs.

Lions' run defense vs. Vikings RB Adrian Peterson: The Lions held the Bears to 2.9 yards per carry Sunday. Peterson was held to 1.5 yards per carry Monday night at New Orleans. The Lions did a decent job against the Bears, but Chicago quarterback Kyle Orton had a career day in the meantime. And Peterson ripped through the Lions last year at the Metrodome, with 15 carries for 116 yards and two touchdowns.

Vikings S Darren Sharper vs. Lions QB Jon Kitna: Sharper has intercepted 11 passes against the Lions and returned two of them for touchdowns. Kitna has thrown three picks to Sharper. From Scott Mitchell to Charlie Batch to Joey Harrington to Jon Kitna to J.T. O'Sullivan, Lions quarterbacks have been struggling against Sharper. No matter who plays quarterback for the Lions today, he must keep an eye on No. 42.

INJURY IMPACT: The Lions likely will have a new starting quarterback for the first time since 2005. It doesn't look like Jon Kitna will be able to play because of his back. That means the Lions will go with Dan Orlovsky, who has knee and ankle injuries himself and already was not very mobile, or Drew Stanton, who has been hampered by injuries and just went through his first week for regular-season practice in his NFL career. Travis Fisher's knee injury, along with Brian Kelly's benching, could mean playing time for Keith Smith or Ramzee Robinson at corner. If Stephen Peterman plays with a cast on his broken left hand, he might struggle because the playing cast has no fingers.