Power Rankings: No. 21 Minnesota Vikings

A weekly examination of the Vikings' ESPN.com Power Ranking:

Preseason: 17 | Last Week: 17 | ESPN.com Power Ranking since 2002

The Vikings slipped four spots this week after a season-opening loss on the road to the Lions, but they could slide even further if they can't quickly remedy some of the issues that developed during the 34-24 defeat. As usual, quarterback Christian Ponder is at the top of the headlines after throwing three interceptions (and botching a handoff with Adrian Peterson that led to a fumble) in the loss, but the Vikings also missed defensive tackle Kevin Williams as they tried to slow down Lions running back Reggie Bush, and Detroit's quick passes neutralized the Vikings' pass rush, which is the strength of their defense.

Heading into Chicago this weekend, it wouldn't be surprising to see the Vikings face a similar game plan to what they saw in Detroit. The Bears will try to use Matt Forte to draw attention away from Brandon Marshall, much as the Lions did with Bush and Calvin Johnson, and Julius Peppers and company could have Ponder once again struggling to make plays under pressure. The Vikings haven't won in Chicago since Peterson was a rookie in 2007, and they'll have their work cut out for them trying to avoid an 0-2 start this weekend.