Week 6 of the NFL season is here, and there are teams who appear to be on their way to a winning record and playoff contention. But in a league with such parity, there is always the opportunity for an upset, and many favorites with winning records could find themselves upset during this week's action.
But who are the most likely candidates for an upset?
New England Patriots
The Patriots earn the "favorite" tag this week against the New Orleans Saints, according to FootballLocks.com, which is likely a result of their home-field advantage and nothing more.
The Patriots have only fallen at home in two of their last 14 home games in the regular season, and one of those was a narrow defeat to the Super Bowl runner-ups from San Francisco last year. Clearly playing at Gillette Stadium is a big advantage for the Patriots.
But the Saints will offer a much tougher challenge than the Jets and Buccaneers, who were the previous home victims for New England.
New Orleans has a high-powered offense led by the arm of Drew Brees and the hands of Jimmy Graham, and they're also getting great contributions in the short passing game and the running game from Pierre Thomas and Darren Sproles.
But it's their defense which has been most impressive, and that's what will be the cause for an upset on Sunday. New Orleans has given up their fair share of yards, but they're in the top four in the league in both turnover differential and points allowed on defense.
Tom Brady is still not on the same page as his young wide receivers (as Aaron and Mike joke about in the video above), and not even the return of Rob Gronkowski would be enough to overcome the opportunistic New Orleans defense and outscore their pass-happy offense.
Kansas City Chiefs
The Chiefs have been a surprising team this season, led by new coach Andy Reid and San Francisco castoff Alex Smith at quarterback. They have yet to lose a game, but they have also yet to play a game within their division.
Their first test of AFC West competition comes this Sunday when they take on the Oakland Raiders, who are coming off of an inspiring win over their rivals from San Diego. Terrelle Pryor is looking more and more comfortable under center for Oakland, and the Oakland defense has been better than expected against the run so far this year.
Oakland has yet to allow a run of greater than 20 yards this season, and Kansas City has only rushed for more than 20 yards on one play this year. And with Alex Smith's limited arm strength, the Raiders can employ a "bend, don't break" mentality on defense and then attempt to outscore Kansas City with their talented offense.
It will be very difficult for the Raiders to fly to Kansas City and pull out a victory, but they have the tools to make it happen. The Chiefs have been rushing the passer with great success this year, but Pryor has the athleticism to escape the pass rush and move the ball with his legs.
If Kansas City can't get the running game going, Oakland has the firepower to get a lead that the Chiefs might not be able to recover from. This is a risky game for the undefeated team from Kansas City.
Detroit got off to a hot start this season, with running backs Reggie Bush and Joique Bell carrying and catching their way to fantastic numbers. They suffered a setback against the Green Bay Packers, but that's to be expected for the Lions.
So they get a chance to redeem themselves and resume their winning ways against the Cleveland Browns, who seemingly gave up on their season when they traded away running back Trent Richardson.
Except they've won three straight games since the trade.
Cleveland has talented receivers and a formidable defense, and they're going to give the Lions a very tough task on Sunday at FirstEnergy Stadium.
Going on the road and facing a team with a talented defense spelled a loss earlier this year for Detroit, who fell to the Cardinals in similar circumstances. And while the Browns don't have the same sort of savvy veteran under center as the Cardinals do in Carson Palmer, they have enough talent to produce the same result.
Calvin Johnson is still returning to health after a knee injury, and missed practice on Wednesday. If he's not at 100 percent, the Lions are going to have problems breaking down the Cleveland defense, and that's a recipe for an upset.
The Colts make a long trip out to the west coast this week to face the Chargers on Monday night, which instantly signals possible upset. Teams coming from east to west don't always have the most success, with time changes, climate changes and unfamiliar settings all coming into play.
Add in the fact that the Chargers are eight points away from being 4-1 (the same as the Colts), and there's no longer a clear favorite for this prime-time matchup.
San Diego has received improved play from their quarterback Philip Rivers so far this season, who has been more careful with his passes and more accurate, as well. That will be the preferred method of attack for the Chargers, although they may also opt to go after Indianapolis by exploiting their greatest weakness.
The Colts give up an average of 129 yards per game on the ground, which means that the San Diego running backs could have a big night on Monday. Ryan Mathews status is in doubt for the game after suffering a concussion, according to Mike Wilkening of ProFootballTalk, but Ronnie Brown and Danny Woodhead are both capable runners who can gain ground against the Colt defense.
The Chargers have to win the turnover battle to pull the upset, which is something they have struggled with this season. But if Philip Rivers can continue his smart, accurate play and the Chargers can generate a rushing attack, they will get into a shootout that leads to a surprising victory.