One quarter of the way into the NFL season, and six teams still have unblemished records.

Cincinnati, Green Bay, Atlanta, Denver and Carolina are 4-0. New England, which had last weekend off, is 3-0.

Compare that to last season, when nobody reached 4-0. Arizona and Cincinnati were 3-0 after the first month, but both lost their next games.

It might not surprise people the Packers, Broncos and Patriots are unbeaten. But it raises eyebrows the Falcons and Panthers — fixtures in the mediocre NFC South — would be pristine at this point.

A look at the NFL's Spotless Six:

NFC

Green Bay: Aaron Rodgers has been so sharp, he has made games look like seven-on-seven passing drills. Although Chicago's Matt Forte tore through Green Bay's defense in the opener, the Packers have shored up the holes against the run and are getting particularly good play from a slightly slimmed-down B.J. Raji.

Carolina: The Panthers are the most surprising 4-0 team, and they haven't been overly impressive in any of their four victories, which came against teams that are all 1-3 now. Still, a win is a win, and Carolina has won eight consecutive regular-season games, a run that started last December after the Panthers staggered to a 3-8-1 start.

Atlanta: Three games into the schedule and the Falcons had already made NFL history. They are the first to open a season with three victories after overcoming fourth-quarter deficits. That teaches a team mental toughness and resiliency. They followed that with a blowout of Houston last Sunday, which had to be cathartic.

AFC

Cincinnati: In his fifth season, quarterback Andy Dalton is off to a scorching start, and he's training the spotlight on a different offensive teammate each week — tight end Tyler Eifert, running backs Giovani Bernard and Jeremy Hill, receiver A.J. Green. On defense, the team that ranked last in sacks in 2014 is now tied for sixth with 11 — and all have come from the front four.

Denver: The once-pass-happy Broncos have flipped the script and they're winning with their top-ranked defense and a dash of Peyton Manning. They have won their four games by an average of a touchdown, the narrowest points differential of the six undefeated teams.

New England: Although New England took several games to warm up offensively last season, the Patriots have had nary a hiccup in that department this fall, picking right up where they left off in their Super Bowl victory. Typically, Tom Brady is seeing the field better than anyone this side of Rodgers, and tight end Rob Gronkowski is seemingly impossible to cover.