For the first time since 2009, five teams have started the season 4-0. But for Denver, Kansas City, New England, New Orleans and Seattle to remain perfect, they will have to win on the road Sunday, something already accomplished twice by the Chiefs, Patriots and Seahawks, and once by the Broncos and Saints.
Here's a look at Week 5's must-see games.
New Orleans Saints (4-0) at Chicago Bears (3-1)
What a difference a year makes. The Saints started out 0-4 in 2012. Now that Bountygate is behind them and coach Sean Payton is back pulling the coaching reins, football normalcy seems to have returned in the Crescent City.
Miami came into the Superdome Monday night unblemished, but Drew Brees and Co. made the Dolphins' 3-0 record look as suspicious as an underage collegian's I.D. Brees carved up Miami in surgical-like fashion, completing 30 of 39 passes for 413 yards (the 10th 400-yard passing game of his career) and four touchdowns.
Once again, Brees is relying on a host of weapons -- most notably Jimmy Graham and the diminutive but dangerous Darren Sproles. Graham has been the best tight end in the league, with six touchdowns and three consecutive games of at least 100 receiving yards. This week he was named the NFC's Offensive Player of the Month for September, becoming the first tight end in either conference to win the honor since the NFL started handing out the award in 1986. The 5-6 Sproles, a multipurpose threat if there's ever been one, scored his first two touchdowns of the season against Miami and has accounted for 370 yards from scrimmage (93 rushing, 277 receiving). Oh, yeah: He also returns punts and kickoffs, and picks off blitzes as well as anyone.
Knowing they have prevailed over New Orleans in the teams' last three meetings at Soldier Field -- a 39-14 victory in the 2006 NFC championship game and regular-season wins in '07 (33-25) and '08 (27-24 in overtime) -- the Bears may find solace in the wake of their first loss of the 2013 season, a 40-32 setback in Detroit to the NFC North rival Lions.
Lions running back Reggie Bush shredded Chicago's run defense (139 yards, including 112 in the first half) even though the Bears often tried to defend him with eight-man fronts. More worrisome to Bears fans was the performance of quarterback Jay Cutler, whose three interceptions and one fumble took some of the shine off his performances in the first three games.
Bears coach Marc Trestman said Cutler's mistakes are fixable. We'll see when Cutler goes up against Saints coordinator Bob Ryan's formidable defense, which has 12 sacks, seven interceptions and has allowed fewer than 20 points in every game.
Denver Broncos (4-0) at Dallas Cowboys (2-2)
Someone please show me another quarterback in NFL history who had a more spectacular start to a season than Peyton Manning, who at age 37 and less than two full years removed from multiple neck surgeries is simply playing lights out. Through four games, he has completed 75 percent of his passes for 1,470 yards and 16 touchdowns -- without an interception -- for a ridiculous passer rating of 138.0.
Just when we think we've spotted the pinnacle of Mt. Peyton, it turns out another plateau appears above the horizon.
With Manning at the controls of the NFL's No. 1-ranked offense, the Broncos have won their first four games by margins of 22, 18, 16 and 32 points. They have extended their string of regular-season victories by at least seven points to 15. If they can hang 39 on Dallas, they will break the NFL record for most points in a team's first five games.
Who knows what kind of performance to expect from the Cowboys, who followed up their best game of the season, a 31-7 victory over the Rams in Week 3, with their worst effort thus far, a 30-21 loss in San Diego after leading 21-10? Dallas fans can't just keep heaping the blame on quarterback Tony Romo. The league's fourth-rated passer, Romo has completed 72.4 percent of his attempts for eight touchdowns and only one pick.
Despite the prolific passing numbers of the two QBs, the ground game should be a determining factor in this game. Cowboys running back DeMarco Murray ranks third in rushing (356 yards on 72 carries), but he'll be running into the teeth of the league's top-rated run defense.
Seattle Seahawks (4-0) at Indianapolis Colts (3-1)
With four consecutive regular-season victories on the road, the Seahawks have erased the perception that they can't win outside the confines of Century Link Field and the 12th Man. They are 4-0 for the first time in their 38-year history and coming off a come-from-behind, overtime victory in Houston that was jump-started by cornerback Richard Sherman's 58-yard interception return for a touchdown.
Seattle managed to win despite having three of its starting offensive linemen (tackles Russell Okung and Breno Giacomini, and center Max Unger) sidelined by injuries. In addition, valuable defensive end Michael Bennett left the game on a stretcher after suffering a strained muscle in his back when his head was bent back awkwardly.
Given subpar pass protection, quarterback Russell Wilson had to rechannel his inner running back. He rushed 10 times for 77 yards -- both career highs -- including 74 in the second half. Wilson will be the third dual-threat quarterback the Colts have faced this season. They had their hands full trying to stop Oakland's Terrelle Pryor in their season opener but were successful in shutting down San Francisco's Colin Kaepernick on the road in Week 3.
Kansas City Chiefs (4-0) at Tennessee Titans (3-1)
The satisfaction the Titans garnered from last week's win over the Jets was offset by the loss of their quarterback, Jake Locker, who, in a scary moment, went down after being hit by two New York players. The diagnosis of a sprained hip was better than first feared, but Locker is expected to be out four to six weeks.
That means Ryan Fitzpatrick, a free-agent addition in the offseason, will make his first start for the Titans. Fitzpatrick has been around the NFL block. He is a ninth-year player who has started 67 games, including 44 over his last three seasons in Buffalo. In five appearances against Kansas City, he is 4-1 with eight touchdown passes and only two interceptions.
But this is a much-improved Kansas City team. Former Eagles coach Andy Reid has lit a torch under the Chiefs since he came on board last January. They are 4-0 for only the third time in their history and opponents have scored only 41 points. Kansas City ranks second in the league in pass defense and unheralded outside linebacker Justin Houston has 7.5 sacks, which ties him with Robert Mathis of the Colts for the league lead.
Ball security will be big in this game. These two teams have the best turnover differential (plus 9) in the league, and the Titans have yet to throw an interception or lose a fumble.
New England Patriots (4-0) at Cincinnati Bengals (2-2)
One can argue that Bill Belichick is doing the best coaching job of his career. Despite losing myriad offensive weapons during the offseason and quarterback Tom Brady now surrounded by a supporting cast with whom he still is familiarizing himself, the Patriots are unbeaten.
Now that Vince Wilfork, their big, space-eating defensive tackle, has been lost to a season-ending torn Achilles tendon suffered during last Monday night's victory in Atlanta, other Patriots defenders will need to step up their games. One player who already is doing that is Aqib Talib, who is tied for the league lead in interceptions (four) and has given New England its best shutdown corner in years.
The Patriots will be going for their seventh straight road victory in Cincinnati, where the preseason fervor has died down somewhat following the Bengals' 2-2 start. The Bengals have been enigmatic, beating Green Bay at home one week, then losing at Cleveland the next week. With the Steelers off to an 0-4 start and the Bengals currently tied with Baltimore for second place, the AFC North race could be a wild one this season.