This is the time of year when a lot of people in NFL circles talk about the "rookie wall" and how those first-year guys stop producing because their bodies are so used to the football season being over or in pre-bowl mode by now.

"Hitting the wall is something I think most rookies to go through," Vikings defensive coordinator Alan Williams said. "I think that is a real phenomena in terms of guys getting tired or disinterested."

The Vikings, however, are coming off a critical victory in which a pair of rookies helped lead the way. Safety Harrison Smith returned an interception 56 yards for a touchdown, while cornerback Josh Robinson returned another one 44 yards to set up a 5-yard touchdown drive in a 21-14 win over the Bears.

"Both of those guys are coming along very well," Williams said. "Harrison has been consistent from Day 1 and has never played like a rookie. And Josh is starting to play consistent football with the number of reps that he's getting. We're pleased that both guys are making plays and not hurting you. Most rookies hurt you when they play and ours are not. They're actually helping us and contributing to us winning football games."

Williams said he preaches keeping a set routine before and after practice to help break through the rookie wall. One thing he's not willing to do is give them time off in practice, similar to what he does for the veterans over 30.

"You have to pay your dues to get that time off," Williams said.

Same old Chris

Cornerback Chris Cook, who is on injured reserve but can return for next week's game at Houston, is in his second week of practice since breaking his right arm against Tampa Bay on Oct. 25.

"He looked good [on Wednesday]," Williams said. "He put his hands on some balls. He looked like the same old Chris that we saw when he got hurt. I think he's come along well."