Through four weeks of the regular season in the NFL there are still five undefeated teams remaining. The potential for a team to the run the table has always been compelling, and even New England's undefeated season two years ago hasn't dimmed that - especially because the Patriots stumbled in the Super Bowl that year. Football fans want to see another undefeated team badly. So, is there going to be another one this year? It's obviously not very likely, but let's take a look at the chances each squad has:

Denver Broncos - Anyone who says that they saw the Broncos winning their first four games is either a hopelessly loyal fan or a liar. There were so many questions coming into the season - a new coach making waves, a quarterback controversy for the ages, defensive depth issues, and so on - that this team seemed destined to struggle. Yet so far they have looked more than competent on offense and strong defensively. Can it continue? Simply, no.

I could see them being a playoff team, but they are destined to come back to earth sooner or later. The biggest reason to believe that is their schedule. Their strong start has been aided by it. Cleveland and Oakland were deeply troubled opponents, Cincinnati is an incomplete team, and Dallas is struggling with mountains of internal strife.

I don't want to take anything away from what they have accomplished, but they certainly haven't been tested like other teams have. Their next four games provide a much bigger test - New England, San Diego, Baltimore, and Pittsburgh. I can see them winning one or more of those games, but there is almost no chance that they will win all four.

Indianapolis Colts - Like the Broncos, the Colts have benefited from a reasonably soft schedule. Jacksonville, Miami, Arizona and Seattle aren't fatally flawed teams, but none of them are among the elite in the league, and none of them are likely heading for the playoffs. Peyton Manning is off to a very strong start, but that certainly hasn't been hurt by playing those four teams.

The team has a reasonably smooth road to 6-0 thanks to their next two games against Tennessee and St. Louis. Beyond that, though, teams like San Francisco, Baltimore, New England, Houston, Denver, and the Jets provide more speed bumps. This is a good team, but it is difficult to believe that they can overcome a new coaching staff, new key players on offense, and injuries in the defense to win all the way to the end.

Minnesota Vikings - The Brett Favre story this year has been a highly-publicized fairy tale. It has all the elements to be a good story. I guess I'll have to play the wet blanket here.

Like the other two teams on this list so far, the Vikings have played less than a tough schedule. Cleveland and Detroit have obvious problems. San Francisco is good, and would have beaten the Vikings if not for that last second, almost impossible Brett Favre pass. Green Bay came into the season as an expected contender, but they have an offensive line that is ridiculously bad, and that is an impediment to any real success at this point.

Tougher games loom down the road, and it's hard to believe that they will win all of them. Especially because of one other looming fact - their quarterback is 40 years old and has a recent history of injuries.

New Orleans Saints - We knew that the Saints could play offense. Now, with the addition of defensive coordinator Gregg Williams they can finally play a little defense as well. That's a dangerous combination.

I don't want to sound like a broken record, though, but the schedule has aided the Saints' early success. Detroit is early in a massive rebuilding process, Buffalo is a ship without a rudder, Philadelphia was without Donovan McNabb, and rookie Mark Sanchez was destined to be very troubled by Williams' defensive scheme that pressures quarterbacks more than any scheme Sanchez had ever previously seen.

There are tougher games on the horizon, though the Saints are very lucky to have a comparatively soft road schedule. The Saints will need to be lucky, and will have to stay healthy. They'll also have to figure out a way to get the passing offense fired up again - they haven't had an aerial TD in two games.

New York Giants - The Giants play the Saints in two weeks, so one of the two teams will drop off the list then (unless the Giants lose to the Raiders before then, of course). The standard schedule argument can be made here, as well - Washington, Dallas, Tampa Bay and Kansas City are all teams that even a reasonably good team should be beating at this point in time.

The Giants will have to deal with some tougher opponents down the road. In the shorter term they also have to deal with the injury to Eli Manning and the real prospect that they could have to rely on David Carr to run the offense. Like the other four teams on this list, the Giants are not a squad that looks like they can or will run the table.