(Reuters) - It is no shock to find the New Orleans Saints and Denver Broncos with perfect records five weeks into the NFL season but seeing the new-look Kansas City Chiefs among the ranks of the unbeaten may cause a few second looks.
Tied for the NFL's worst record a year ago after going 2-14, the Chiefs have undergone a miraculous transformation sparked by San Francisco 49ers castoff quarterback Alex Smith and discarded Philadelphia Eagles coach Andy Reid.
Only twice in the previous six seasons has Kansas City won more than four games but they suddenly find themselves among the NFL elite after rallying for a 26-17 road win over the Tennessee Titans on Sunday.
At 5-0, it is the best start to a season for the Chiefs since they won nine straight games to open the 2003 campaign.
"We are 5-0 and we're not ashamed of that," Reid said after Sunday's game. "But we also know that we got a ton of room to improve."
Kansas City have climbed to the top behind an energetic defense that has allowed the fewest points per game (11.6) and an offense led by the steady but unspectacular play of Smith.
The Chiefs have also benefited from a soft early schedule that has included meetings against the winless Jacksonville Jaguars and New York Giants.
But they have also beaten some good teams such as the Dallas Cowboys and Tennessee and can look ahead to three straight home games against unthreatening opponents: Oakland Raiders (October 13), Houston Texans (October 20) and Cleveland Browns (October 27).
On November 17, the Chiefs are scheduled to visit the Denver Broncos (5-0) in a game that could very well decide top spot in AFC West and perhaps a showdown between the conference's two remaining unbeaten teams.
While the Chiefs have been grinding out the wins, the Broncos (5-0) and Saints (5-0) have lit up the season with some dazzling offensive fireworks.
Denver quarterback Peyton Manning continued to rewrite the NFL record book on Sunday by tossing four touchdowns in a 51-48 shootout win over Dallas that saw the two teams combine for over 1,000 yards in offense.
The Broncos have now scored 230 points this season - the most by any team through the first five games, while Manning moved past Hall of Famer Dan Marino on Sunday into second place on the career all-time passing list with 61,371 yards.
Manning's 20 touchdown passes this season are seven more than his closest pursuers.
"We talked about it at halftime, we had to keep scoring," said Manning, who threw his first interception of the season but also ran for a rare touchdown. "Their (Dallas) offense is hot. The field goals were disappointing because their offense was scoring touchdowns in the second half.
"But, we kept scoring."
Scoring should not be a problem next week as the Broncos host the woeful Jaguars, in a game that Las Vegas oddsmakers have installed the Broncos as 28 point favorites.
Jacksonville has scored just 51 points all season, while the Broncos scored that many on Sunday in Dallas.
After the Seattle Seahawks lost to the Indianapolis Colts on Sunday, the Saints remain the NFC's only unbeaten team following their 28-16 win over the Chicago Bears.
Only Manning (1,884) has passed for more yards than Drew Brees (1,722), whose Saints are one of just five teams averaging more than 400 yards of offense per game.
With Brees at the controls the Saints have long had one of the NFL's most productive and explosive attacks but it is their defense, that has allowed an average of just 14.6 points a game this season, that has stepped up to help make New Orleans the league's most balanced team.
"The one thing we tried to preach all year is each game takes on a different, not a different meaning, but they are not necessarily played the same way," Saints coach Sean Payton said on Monday.
"Understanding as a team what it takes to win that specific game is something that if your team gets, and I think we are beginning to, is an important trait."
(Reporting by Steve Keating in Toronto; Editing by Frank Pingue)