It's a conclusion in most circles that the Vikings' playoff push will be sabotaged if the Pro Bowl performers are knocked out four games for violating the NFL's policy on steroids and related substances. They're at the center of a Vikings defense ranked second in the league against the run.

''That's out of my control, so I don't focus on that,'' said Vikings defensive end Jared Allen, who has eight sacks this season and six in his last six games. ''Right now we've got 'em, and that's what we're going to play with. But no matter what happens in this league, injury or anything, if someone goes down, the next person has to step up and fill those shoes.''

Kevin Williams, who has 8œ sacks and five passes defended, lines up on the weak side, which means he'll be across from left guard Josh Beekman more times than not.

''It was a great challenge,'' Beekman said of their encounter last month. ''Luckily, I've got that tape to look at and hopefully sharpen my skills a little bit better.''

HEALTH BEAT

Tight end Desmond Clark's sprained right knee sidelined him Wednesday, and strong safety Mike Brown (calf), receiver Marty Booker (knee), defensive tackle Tommie Harris (left knee) and linebacker Jamar Williams (groin) also sat out. Clark has made the most consecutive starts (62) among active tight ends.

''It's something to be proud of,'' Clark said. ''I don't put a whole lot of stock into it. I'm just doing my job, and I have just been fortunate enough to be healthy to do it.''

A sprained right knee in preseason was supposed to sideline him for three to five weeks, but he returned in two. The hope is that he will be available Sunday.

Vikings right tackle Artis Hicks was held out of practice with an elbow injury and might be replaced by struggling former second-round pick Ryan Cook, who was benched last week.

EXTRA POINTS

A scoring change by the NFL just made running back Matt Forte's season-best effort against the St . Louis Rams even better. His seven-yard reception in the third quarter has been changed to a run, giving him 139 yards on 21 carries.

- The Bears signed receiver Travis Brown to the practice squad. The undrafted free agent from New Mexico previously spent time with the Seattle Seahawks and Cincinnati Bengals, from whom he received a settlement for a hamstring injury.

- The Bears will practice this morning and cancel afternoon meetings so players and staff can enjoy Thanksgiving.