This seems to be the year of the underappreciated, underdog, unbeaten team. The Denver Broncos have repeatedly found themselves as underdogs this season despite not losing a game. The Indianapolis Colts were underdogs against Arizona and, maybe even worse, were only favored by a field goal against winless Tennessee two weeks ago. Now this week the 6-0 Minnesota Vikings enter Pittsburgh's Heinz Field as 5.5-point underdogs.

It used to mean something in the NFL to win all of your games. Now it seems as the oddsmakers and everyone else are just waiting for these unbeaten teams to drop a game and go by the wayside with the rest of the mortals, excluding the '72 Miami Dolphins.

The Colts proved the oddsmakers wrong twice, blowing out both above mentioned lines. The Denver Broncos have been underdogs four times, yes four times, this season already. They have won each time.

Will the Vikings continue the trend this Sunday of the unbeatens remaining, well, unbeaten? All signs point to no.

This game differs from the previously mentioned games in that the point spread has little to do with the disrespect for the unbeaten team, but rather recognizing who the opposition is. The Pittsburgh Steelers are the defending Super Bowl Champions. The last time they lost at home it was Week 9 of last season. The Steelers' offense is on pace to become the most prolific offensive unit in team history. The team appears to be stronger now than it did entering the season.

The running game with a healthy Willie Parker and the emerging Rashard Mendenhall has become what Steeler fans are accustomed too. And Troy Polamalu is expected to be at 100-percent for an entire game for the first time this season.

The two knocks against the Steelers this year have been their inability to close out games and of concern to bettors, their inability to cover. The reasons are connected. The Steelers have led by large margins the last three weeks only to watch two of the three opponents creep back in and barely cover the number. For the season Pittsburgh is 4-2 straight up but an abysmal 1-5 against the spread. The Vikings at 6-0 SU and 4-2 ATS are much better against the number. This, however, will be the first time Minnesota enters a game as an underdog.

An overlooked aspect of this week is Brett Favre and the Vikings ability to play outdoors. The weather in Pittsburgh is expected to dip below 50-degrees. Minnesota has not played an outdoor game since Week 1 at a balmy Cleveland. The other five weeks were spent either in the Metrodome or at domes in St. Louis and Detroit. One of the main reasons Favre's only two finalists in his free agent sweepstakes were Tampa Bay and Minnesota was because of weather concerns. While 40-something degrees is nowhere near offensively crippling conditions, the outdoor element will be a drastic change for Favre.

Heinz Field is situated along the riverbanks where the Allegheny and Monongahela Rivers meet to form the Ohio River. The swirling winds from the rivers and the open endzone provide a nightmare for kickers and quarterbacks alike who are not accustomed to it. On top of that, the Vikings, who have been accustomed to playing on different variations of field turf, are now going to play on what is widely regarded as the worst playing surface in the NFL.

The game will come down to a lot more than just the grass the players are standing on but of all the factors involved in this contest, that is the most overlooked one and the one that favors one side (the Steelers) more than any other.

The Vikings are a legitimate undefeated team. They have the running game, the defense and a quarterback who is making the plays he needs to. The Steelers are a 4-2 team in the body of a 5-1 or even 6-0 team. The home field advantage and away disadvantage for the Vikings is enough to warrant a play on the Steelers even with the line at -5.5.