This isn't going to be easy for Evans. He has seen plenty of playing time in passing situations but he is now taking over for one of the NFL's premier run stoppers.

The Vikings have the NFL's best run defense, but they are about to face two premier rushing teams in the Falcons and Giants. Williams is expected to miss a month so the Vikings will have to make a run in the playoffs to get him back on the field this season.

PLAYER NOTES

--DE Jared Allen did not practice Wednesday because of a sprained MCL in his left knee. Allen missed practice last week on Wednesday and Thursday because of the injury but played at Arizona while wearing a brace and had two sacks.

--QB Gus Frerotte was limited in practice Wednesday because of a broken bone in his back that kept him out of last Sunday's game in Arizona. Frerotte split snaps with Tarvaris Jackson in practice, according to coach Brad Childress.

--RT Artis Hicks did not practice Wednesday because of a partially torn right triceps that has kept him out of two of the past three games. Ryan Cook has started in Hicks' place. Hicks might be able to return this year but he likely is going to need surgery when the season is finished.

--RB Adrian Peterson was added to the injury report because of an ankle injury that limited him Wednesday.

--WR/KR Darius Reynaud did not practice Wednesday. He missed the Arizona game because of a toe injury suffered the previous week at Detroit.

--DE Brian Robison was limited Wednesday because of a knee injury. Robison played Sunday, 12 days after having arthroscopic surgery to repair the injury.

GAME PLAN: The Vikings top-ranked rushing defense will get a tough test, facing one of the NFL's best running teams. There is no doubt the loss of Pro Bowl nose tackle Pat Williams could hurt Minnesota in this one.

The Falcons, who are tied with the Giants for the NFL lead with an average of 148.7 yards per game on the ground, are likely to go right after Fred Evans, who will replace Williams as the starter at nose tackle. Nonetheless, a run defense that is giving up only 71.2 yards per game still has Pro Bowl defensive tackle Kevin Williams in the middle.

The Vikings' performance in this game will be crucial because they will face the Giants in their regular-season finale. If the Falcons have success in the run game then the Giants are sure to follow with the same plan.

The Falcons are not completely one-dimensional team on offense. Rookie Matt Ryan leads a passing offense that is ranked 13th in the NFL (218.4 yards per game), but the Vikings pass defense should have plenty of confidence after a solid performance last Sunday at Arizona. Minnesota gave up 298 yards through the air but that was only because the Cardinals attempted 50 throws and only seven runs.

Offensively, the Vikings will look to get a second consecutive solid start out of quarterback Tarvaris Jackson. This will be Jackson's first home start since Week 2 of the season, and it will be interesting to see how he handles the potential pressure.

The Falcons are ranked 23rd against the pass and 22nd against the run, so the Vikings should be able to have some success. As is usually the case, Minnesota will look to establish the ground game with Adrian Peterson and mix in some deep passes.

MATCHUPS TO WATCH: Vikings NT Fred Evans vs. Falcons RB Michael Turner - Evans, starting in place of injured Pro Bowl NT Pat Williams, will get an immediate test. Evans will be counted on to help slow down Turner, who is second to Adrian Peterson in the NFL with 1,421 rushing yards. Evans will have the advantage of having Pro Bowl defensive tackle Kevin Williams beside him.

Vikings CB Cedric Griffin vs. Falcons WR Roddy White: Griffin has shown substantial improvement as the season progressed, and he could get another tough test this week. White is second in the NFL with 1,310 yards receiving and eighth with 82 receptions. He was named to the NFC Pro Bowl team this week. Griffin spent much of last Sunday's game matched up against Cardinals Pro Bowl receiver Larry Fitzgerald and limited him to five catches for 52 yards and no touchdowns.

INJURY IMPACT: The absence of Pro Bowl nose tackle Pat Williams means Fred Evans becomes a starter and the recently signed Jimmy Kennedy probably gets a role in the defensive rotation. Rookie Letroy Guion also is a candidate to get some playing time. Jared Allen continues to play with injuries, but the Pro Bowl defensive end has 14.5 sacks and doesn't appear to be slowing down no matter how banged up he might be. Tarvaris Jackson would seem likely to remain the starting quarterback in place of Gus Frerotte as long as Jackson continues to perform at a high level.