Vikings at Redskins -- Week 6

Where: FedEx Field, Landover, Md., (grass, outdoors)

When: Sunday, 4:25 p.m. ET (FOX)

Spread: Redskins by 1.5

Records: Vikings (Overall: 4-1, NFC North: 1-0); Redskins (Overall: 2-3, NFC East: 0-0)

Past results: Two most recent meetings – Dec. 24, 2011: Vikings 33, Redskins 26; Nov. 28, 2010: Vikings 17, Redskins 13. Series record: Redskins lead the series 11-10.

What matters: Perhaps the biggest X-factor in this matchup is whether Washington QB Robert Griffin III will play on Sunday. Griffin suffered a mild concussion last week, was cleared to practice on Wednesday and will likely be on the field on Sunday. But the concussion might take away one of his weapons. Griffin is the leading rushing quarterback in the league with 241 yards, and the Washington coaches were already beginning to limit his attempts before he was concussed. Griffin leads the league in passing accuracy. But even though Griffin’s concussion likely won't keep him off the field, it will likely affect the Redskins’ game plan. But not the Vikings’.

“If he plays, you’ve to be more aware of his scrambling abilities. But the game plan doesn’t change,” DE Jared Allen said. “They’re doing a great job of running the ball right now. So it is going to be a big challenge for us to go in there and stop the run. We have to force them to be one-dimensional.”

Who matters: QB Christian Ponder should be able to find some success against Washington’s pass defense, which is currently ranked 31st in the league (giving up 328.6 yards per game). It is not known whether he will bewithout his deep threat WR Jerome Simpson, who was limited last Sunday with a leg weakness that was reportedly related to a back injury. Simpson responded to treatment and coach Leslie Frazier was hopeful to have Simpson active on Sunday. With or without him, the Vikings have been productive in the passing game thanks to versatile WR Percy Harvin, who has suddenly made the bubble screen a household name. Harvin ranks secnd in the NFL with 38 receptions, but he catches a lot of his passes in bubble screens and earns plenty of yards on his own, as he leads the NFL with 242 yards after catch. If Simpson can’t go, a greater focus will fall on Harvin, so the Vikings will try to get Simpson ready for this one.

Key matchups: The Redskins' rushing offense is ranked No. 4 in the NFL, while the Vikings' rushing defense is ranked sixth. Rookie RB Alfred Morris, who was picked in the sixth round, has been a nice surprise in Washington, as he has 491 yards (fourth-most in the league) on 100 carries and has scored four times. The Vikings defense, on the other hand has heldopponents to an average of 2.84 yards rushing on 1st down, which is tops in the NFL. They also have allowed only one rushing touchdown in five games this season. When the Vikings' defense meets the Redskins rushingoffense, something has to give.

“Morris runs hard,” Allen said. “We just got to wrap up and tackle. Everybody has to be in their gap. They do some stuff scheme-wise to get you moving east to west. From a defensive line standpoint we all get excited about it. We’re always up for it. It should be fun. They are very balanced offense when they run the ball, so we have to take that away.”

Injuries of note: If Simpson plays (he is recovering from weakness in his leg caused by a back injury) it will be interesting to see how long he can go -- last week he played 24 of 69 offensive snaps. RB Adrian Peterson tweaked his left ankle on his first rushing attempt last Sunday, but he played the whole game with it. He sat out of practice on Wednesday, as he was experiencing a little soreness, but he practiced on Thursday and expects toplay on Sunday.

Inside stuff: Harvin has caught a pass in every game in which he’s played in his career, including playoffs (52). Harvin also has a way of getting into the end zone. He is one of only three players in NFL history with a rushing, receiving and kick return TD in 3 consecutive years. Last weekend, Harvin joined Chicago RB Gale Sayers (1965-67) and Philadelphia RB Timmy Brown (1961-63) in the exclusive class.

The Vikings' defense also has been playing well. Its 64 sacks since the start of the 2011 season is first in the NFL. During that same time period, the Vikings have the second-most forced fumbles (23) and fumble recoveries (20) in the league.

Connections: Former Vikings cornerback Cedric Griffin (2006-2011) and safety Madieu Williams (2008-2010) are manning the secondary for Washington. Williams has started five games while Griffin has played in (but not started) three games. WR Emmanuel Arceneaux, who played last season for Minnesota and was in camp this season, is on the Redskins practice squad.

Stat you should know: Ponder is completing his passes at a high rate (69 percent) and he trails only one player in the NFL: Griffin III (69.1 percent).

 The Vikings have scored on all 15 of their trips to the red zone in 2012 (six touchdowns and nine field goals), which is tied for the league lead in red-zone scoring efficiency.

Record watch: Last Sunday, Peterson came up 12 yards short of 100 yards and his 29th career 100-yard game, which would tie Robert Smith for the team record. On Sunday, Peterson will play on the same FedEx Field where he tore the ACL and MCL in his left knee at the end of last season.

Bulletin board quote: Peterson was asked if he would welcome the chance to run over Redskins S DeJon Gomes, the Redskins defender who hit him last season and caused his knee injury.

“Of course,” said Peterson, laughing. “I will make sure I have my shoulders low. He might be trying to go for the ankles, though. I am just going to go out andplay football and have fun.”

Looking ahead: The Redskins travel to New Jersey to take on the New York Giants in their first NFC East Division game of the season. The Vikings return home to host the Arizona Cardinals for the sixth time in the past seven years.

Prediction: Vikings 24, Redskins 17

For more Vikings news and notes, follow Joe Oberle on Twitter @CBSVikings and @joeoberle.