Redskins.com looks at two key matchups to keep an eye on during Sunday's Redskins-Vikings game at FedExField.
"Redskins-Vikings: Marquee Matchups" is presented by Papa John's.
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Trent Williams vs. Jared Allen
From DeMarcus Ware to Mario Williams to Dwight Freeney to Julius Peppers, Trent Williams matchups this season have been one elite pass rusher after another.
In eight games this season, Williams, the Redskins' first-round draft pick (fourth overall) in last April's NFL Draft, has seen just about every move in the book.
He has had to adapt to the speed of the game and spend time watching film to adjust to various stunts and blitzes that he did not see at the college level.
However, Williams may not have lined up against a player the caliber of Jared Allen yet.
Allen has speed and spin moves like other pass rushers, but he has a quick first step and a relentless motor that can be tough for a veteran left tackle to handle, let alone a rookie.
Since 2004, Allen's 78.5 sacks lead the NFL. He had 14.5 sacks each of the last two years playing on a defensive line that includes Pro Bowl defensive tackles Pat Williams and Kevin Williams.
Allen got off to a slow start this year, with just one sack in the Vikings' first seven games. But he has re-emerged in the last three games, posting 5.5 sacks.
London Fletcher vs. Adrian Peterson
The Redskins have struggled in run defense in recent weeks, yielding 151 rushing yards to Chris Johnson and the Tennessee Titans last week and 260 rushing yards to the Philadelphia Eagles in Week 10.
As a result, the defense has dropped to 27th in the league in that category.
London Fletcher leads the Redskins with 116 tackles this season. He has posted 12 consecutive seasons with 100 tackles, the longest streak among all NFL defenders.
Fletcher has a nose for getting in position to make plays and he uses sound fundamentals to ensure that he brings down ball-carriers on contact.
For the second week in a row, the Redskins face an elite running back, this time in Adrian Peterson. He enters Sunday's game with 980 rushing yards and seven touchdowns on 211 carries. He is also effective in the Vikings' short passing game with 31 catches for 297 yards.
At 6-1 and 217 pounds, Peterson combines good size with breakaway speed. He can be tough for one defender to bring down as a result.
The Vikings' offensive line is one of the toughest in the league, especially on the left side with Pro Bowlers Bryant McKinnie and Steve Hutchinson. For Fletcher and the Redskins' defense, fending off blocks to get to Peterson is going to be a key.