NFC's unexpected contenders to match up

Sunday's matchup offers some very interesting opposition for the Vikings' star players.

EDEN PRAIRIE, Minn. — The Minnesota Vikings and Arizona Cardinals are two of the surprise teams in the NFC this season, with both teams near the top of their respective divisions.

They've had success in similar ways, starting with strong defenses. But both teams are coming off losses which have momentarily changed the outlook of their seasons. Minnesota (4-2) is trying to prove last week's loss against the Washington Redskins and dynamic rookie quarterback Robert Griffin III was a fluke. Arizona has lost two games in a row after a surprising 4-0 start.

Here are five things to watch as the Vikings host the Cardinals and both teams try to get back on the winning track:

1. A salivating matchup for Minnesota defensive ends Jared Allen and Brian Robison.

Allen and Robison, who combined for 30 sacks last year but have just five total this season, would seem to have the type of matchup they can build up their sack numbers. Arizona has allowed a league-high 28 sacks and tackles D'Anthony Batiste and Bobby Massie have been a big part of the total. Batiste is playing left tackle for the first time in his career. Massie is a fourth-round rookie.

Behind the struggling line, the Cardinals are going back to quarterback John Skelton after Kevin Kolb was injured last week and Skelton isn't as mobile as Kolb, who was sacked 27 times this season. Arizona has allowed 22 sacks the past three games. Allen, after going without sacks his first two games, now has a sack in four straight games. Robison has just one sack. Though the two say they aren't any more eager for this matchup than any other, they have to be excited for the potential Sunday.

2. A likely matchup between two elite playmakers at their position and on special teams.

Vikings' receiver Percy Harvin leads the league with 49 catches and is seventh with 540 yards receiving. Harvin is the biggest playmaker for Minnesota's offense right now. The Cardinals have cornerback Patrick Peterson, the fifth overall pick in the 2011 draft, who is developing into one of the league's top cover corners. Peterson is tied for third in the NFL with three interceptions this season, including one in each of the past two games. The two emerging stars likely will be matched up often on Sunday.

But Harvin and Peterson aren't limited to just their offensive and defensive responsibilities. Harvin is the league's leading kickoff returner with a 37.1-yard average and a touchdown. Peterson is an explosive punt returner, returning an NFL-record four punts for touchdowns as a rookie, and is averaging just 10.1 yards-per-return this year.

3. The Vikings' secondary against the hometown star.

Minnesota owns one of the league's top run-defenses and the Cardinals are 27th in the league running the ball after injuries have sidelined their top two backs, Beanie Wells and Ryan Williams. William Powell is now the leading ball carrier and if the Vikings can turn Arizona one-dimensional on offense, it will fall on Skelton and receiver Larry Fitzgerald, a former Minnesota prep star. Fitzgerald is eighth in the NFL with 36 catches for 430 yards and three touchdowns.

The tall, sure-handed receiver has good jumping ability as well and can be a matchup problem for the Vikings. In five career games against Minnesota, Fitzgerald has 35 catches for 540 yards and a touchdown. This Vikings' secondary could be different though. Minnesota held Detroit's All-Pro receiver Calvin Johnson to five catches for 54 yards. Indianapolis' Reggie Wayne had six catches for 71 yards, but had a big touchdown. In all, the Vikings' defense ranks 10th in the league against the pass and 11th against the run.

4. A big test for Minnesota's offensive line and quarterback Christian Ponder?

Arizona's surprisingly stout defense has more sacks that the Vikings this season, meaning Minnesota's offensive line will be under pressure to continue its improvement. The Vikings re-worked line has played well at times this season, but struggled against Washington last week. Meanwhile, Ponder had three turnovers and several misfired passes due to poor footwork.

Defensive tackle Darnell Dockett, a three-time Pro Bowler, paces the defensive line, and end Calais Campbell has two sacks. Linebacker Daryl Washington is playing at an All-Pro level with 54 tackles, seven for loss, four sacks and seven quarterback pressures. He also has forced two fumbles. Linebackers Paris Lenon, O'Brien Schofield and Sam Acho have combined for nine sacks. With the pressure applied on opposing quarterbacks (19 total sacks), the Cardinals are ninth in the league against the pass and are a plus-4 in turnover ratio causing 13 turnovers this season. Minnesota is a minus-1 in turnover ratio.

5. Vikings need to finish drives.

Three early drives against Washington last week ultimately doomed Minnesota after it was forced to settle for field goals in the red zone, accounting for a 9-0 lead. The Vikings have points on 95.5 percent of their red zone trips this season, but are tied for just 17th in the league with 50 percent touchdowns in 22 red zone opportunities.

The struggles on finishing drives with touchdowns has been a focus this week. Offensive coordinator Bill Musgrave said it was his fault for Harvin not being on the field for five of the nine red zone snaps early last week. The Vikings also have tight end Kyle Rudolph and running back Adrian Peterson, two big weapons in short yardage. Minnesota has the pieces to be effective in the red zone, but have failed too often. In what could be a close game Sunday, the Vikings will have to capitalize when they get close to scoring.

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